If you plan on using iron sights you will also need a carry handle assembly or one of the rear sight assemblies that attach directly to the rail. If you are planning on using optics exclusively, you might as well go with a “shaved” front sight base.
Mil-spec. Good choice. The only potential drawback will be excessive muzzle flash. With that short of a barrel, the muzzle flash will be downright blinding when shooting during low light level conditions. The short barrel will also reduce muzzle velocity a little bit, but I wouldn’t be concerned about that unless you plan on shooting long distances.
Top it off with an EOTech holographic sight, and you’ll be the envy of your shooting buddies. 
Let’s eliminate that flash entirely with an AAC Blackout. This is the non-mount version, and is a little less than the threaded version if you never intend to mount a suppressor.
You don’t believe me? You will, Dr. Jones. You will become a true believer. 
An Eotech or Aimpoint can be mounted far enough forward to clear your headgear, but you can eliminate that problem altogether with just one more accessory 
TheM4-2000 is the best 5.56 suppressor made, and if you use subsonic rounds, it’s what we callo"hearing safe". Still, I’d really consider the .300 Blackout upper instead.
AAC designed the round from scratch to be lethal AND quiet. It uses standard AR mags, and you can always put on a 5.56 upper anytime.
Hope I can bump this without causing any moderator wrath.
I just got it finished. Here’s a picture with my recently aquired 7 mm mauser!
Nice I am jealous
CAPT
Now we need a Range Report.
How hard is it to put one of those assemble yourself kits together?
It was very easy. I got the lower (the registered ‘gun’ part) which is just a milled hollowed out shell with the proper holes for everything. I bought the PSA kit mentioned above that came with everything else except the rear sight and magazines. My friend sent me a couple of links that really show how to do it exceptionally well. http://www.youtube.com/watch?v=iA_Vkb2UB1w
They forgot to include the trigger and hammer pins so I had to wait 3 days extra for those to come in; but total assembly time was 30 min or so with the help of my friend. If you are alone and using the linked video, it might take you 45 min. Its very easy, but watch out for the small springs and detents; they are tiny and could easily be launched across the room, never to be seen again.
BTW: I didn’t get the 270 mentioned in my original OP. I was told it was a 270 before I got it…It turned out to be the 7mm Mauser pictured upthread. (Here’s a related thread I started shortly after this one 7mm Mauser (winchester model 70) - In My Humble Opinion - Straight Dope Message Board
With a small number of tools (none of them very specialized) and good instructions, it’s pretty easy to assemble the lower receiver, which comprises most of the moving parts. I’ve built three AR-15s, looking forward to doing more. I haven’t tackled the job of assembling the barrel to the upper receiver yet, because I get the impression that can be tricky in terms of safety and accuracy. I’ve left it to professionals and just bought completed uppers.