pulykamell, I’d be glad to answer your questions, but I probably risk being accused of a hijack for this thread. Nevertheless, because I feel it does relate to the OP, here goes…
I had a blank check. For artistic reasons, I would have been overjoyed to work with John Williams to make these decisions, but I wasn’t given that freedom or that kind of (hourly) budget. Basically, the job was “push it out, get it out, never mind the accuracy, we just need something on paper, and fast,” ordered by the publisher.
Unfortunately, I no longer have any of my output to refer to (I left most of it behind when I moved away from LA, and I regret it ever since), so I’m not sure exactly how I notated it.
If you remember that a lead sheet is basically a melody, a harmony, and a lyric (if any), I’m sure I tried to capture the primary melodic line & rhythm, harmony in the form of chord symbols if at all possible (and that isn’t always easy for orchestral works), and lyrics weren’t a consideration here. Most likely I used a single melody line with cues where important. IMHO, using a lead sheet for this kind of task is ridiculously stupid, but sometimes you gotta do what you gotta do.
Publishers didn’t seem to understand that if any written music or lyric sheets were used during the recording, they might be incredibly useful (for speed and accuracy) to anyone doing a lead sheet or transcription of any kind. They seemed to think that any copyist could write a 100% accurate transcription of what every instrument was playing, in a few minutes, just by hearing a stereo recording of an orchestra. They were used to lead sheets for simple country songs and assumed that a jazz or symphonic work was no different
It was after I had a hard time figuring out what Barry White was saying, and finding out that the written lyrics were available, but not given to me, that I started charging about 30% more if a lyric sheet was NOT supplied, and warning the publishers that the shortcomings of my ear didn’t guarantee an accurate lyric.
I built my own equipment, or modified consumer hifi as needed. I was given open reel tapes (different speeds), acetate disks (different speeds), pressed disks (different speeds), and later, cassette tapes and had to be able to use what was given.
I transferred disks to open real tape for ease of handling. There were no consumer or even pro-sumer open reel tape units available that had speed controls. The studios had VSOs (Variable Speed Oscillators) that could control their tape machines to any speed, fast or slow, but a VSO cost thousands of dollars and the tape machines were prohibitively expensive.
So I built a Knightkit audio generator and bought a 100 watt mono audio power amp. I rewired a Pioneer RT-1011 tape deck that had a synchronous capstan motor to accept its power from the audio generator thru the power amp. 60hz from the audio gen, amplified, provided standard power (a synchronous motor’s speed is dependent upon the frequency). I was able to reduce the tape speed from 40% of normal to about 250% by varying the audio frequency, and the audio generator allowed very fine tuning around the “standard” speed. This was critical, since I used a non-tunable standard piano as a pitch reference and to play along with the recording.
This proved to be immensely valuable since I found out that while professional recording studios go to great pains to have their tape recorders play a constant speed, they seemed to have little concern that the constant speed was referencing 440hz for A. They put level tones at the start of each multi-track tape, but never (to my knowledge) used them to calibrate speed, only level.
So by the time a multi-track master was mixed down to a 2-track stereo (might be 1% off in speed), then given to the disk mastering lab, whose machine might be 1% off, too, the speed errors sometimes accumulated (2% speed low or high is a large fraction of a musical half-step). Many commercially mastered disks are significantly out of tune with a 440hz base.
So I had to compensate. In the worst case, a disk might be exactly 1/4 tone away from standard, and I had to guess what the intended pitch was. If it was a guitar piece, I leaned towards pitches that would make the composition in a “sharp” key. If it was keyboard-based, the key of C was more likely than D-flat or B.
I guessed wrong once, for a Norton Buffalo LP. The performer/writer called me up and loudly accused me of writing “the entire album in the wrong key! All the songs are wrong! Every chord is wrong! Every note is wrong!” He calmed down when I suggested he look at them in a transposed fashion, and they would all be right, and if he had told me the keys in the first place, I would have tuned my recorder to match. He subsequently told me that all the note and chords were right after all. 
Unlike today’s digital processing, where you can boost the speed without the pitch, and vice-versa, I had to put up with both changing at once, and compensate, so I did a lot of transposing in my head.
My favorite example is Billy Joel’s Root Beer Rag, from his Streetlight Serenader album. I slowed the recording down to get the individual melody notes easier, then sped it up to get the bass notes easier. I remember the publisher telling me they were in a hurry for the lead, and before I heard the song, I told them I’d get it done in about an hour. When I first played it, I called them back and told them I would need a little more time – it wasn’t your typical country ditty!
Yes, in standard chord symbols. For complex songs, something has to give, but I did my best.
I sometimes had a disagreement with songwriters about this. I felt that the chord symbols should reflect the harmony, not the chord the guitar or keyboard was playing. If the songwriter was a guitarist, he wanted the chord symbols to show his part, not the overall harmony. Cat Stevens wanted it to reflect the piano part, which he played. (Imagine me arguing with Cat Stevens?)
Again, I was given a blank check. Rarely did my work get back to the original composer/artist, nor did they care, or would they know how to read it. They were too busy counting their booze, broads, and bills.
On the rare occasions that I was challenged (and that’s another story), I always held my ground, and invited the complainer to come to my studio and we’d examine his complaint. I never lost one of these arguments.
I can’t recall running into many problems like this, although I often discussed such topics with academics, and Clinton Roemer proposed a notation methodology for 4th-based chords. On the rare cases where a lead sheet just didn’t make sense, I advised the client to consider working with me on an hourly basis for a custom job – “this is not your grandfather’s lead sheet, you dig?”