Yeah, whites along the Gulf coast. I’m pretty sure you find more non-rhoticism in black English, though., although on-rhoticism is disappearing in America these days in general
I could call and talk to you if you want, I live just North of Jackson MS. The folks I know who live there sound normal to me so I am sure we have similar accents.
Y’all is always always plural never singular.
the g on ing is pronounced but it is soft but that is mostly the case, the letters are proounced just really really lightly
a child would never refer to an adult by their first name alone, a close family friend would be called Miz Jane or Mister John. A really close family friend would be an honorary aunt or uncle.
Mrs is pronounced Miz down here
the Scarlett accent with the lost r is more Georgia than Mississippi
think hot lazy tired way of speaking, 100 degree heat with 100 percent humidity which is not uncommon on the delta will make everybody talk southern.
Don’t really know about the “no religous swearing” part, It is unlikely that we would cuss in front of our parents, grandparents or preachers but we often take the Lord’s name in vain just like everyone else it just sounds more lyrical when we do it.
Accents are often on differnt places, the emphasis is often on the first syllable for instance police is POH-lease. and we often add more length to a word but I am not sure how to show that.
Delta Burke, Cybil Shepard and Dixie Carter might be a good examples. Watching cops set in Mississippi (or in Memphis) might be helpful for an authentic dialect.
Adhemar in Me-fuss
**Actors with a genuine (or convincingly faked) rural Mississippi accent? **
You do realize that, during the 70’s, Jackson wasn’t the same as “rural”? 
I grew up in North Mississippi. I used to be able to tell what area of the state someone was from, by their accent, but not any longer. Back in the 70’s, in Jackson, there was a brassiness to a woman’s way of speaking. And white folks were more twang-y back then, too.
As far as accents which sound close, maybe Lee Ann Rimes (I know, she’s not an actor). She was born in Jackson, in 1982. Or maybe Delta Burke.
Since when is a 3-hour drive “just North”? You are a WAYS up the road, dude. 
A far piece!
Not going to be much help with available movie examples, as I don’t watch em much.But, have lived in the South for 33 years: NC, Mississippi for 13, back now to NC. Mississippi is definitely a softer accent than NC or TX, softer still if you go out into the Delta region. Now, back in NC, I delight in hearing a Mississippi accent from someone, and can peg it quick; just delightfully soft, and slower.
That would be the main thing i’d advise, especially with your time frame of the 70’s, before media changed people’s speech patterns. Slow the speech down in a soft sense, and don’t hurry it, but do it thoughtfully, not like an idiot drawl, 'cause that’s really annoying and condescending.
Example: M’am, I really don’t know how you think I should speak; I’m just talking.
Might be more like: “Maa’am, Ah rah-llly donnn’t know hahww yahh thannk Ahh shou’dd spahk; Ahhmm jes’ tahhkin.”
Again, don’t think “slow” in a drawl as being any indication of slow in mind, but soft, and, rather thoughtful in speech. That’s been my experience as a born Californian transplant, albeit for the better part of my life.
In preview, I see adhemar’s post, good advise. To add to that, Memphis can be, depending on yer accent within a 50 mile radius:
Me-fuss
MIM-fuss
Mehphy
Meh-um-fuss
Viva Las Difference!
Gah! No it isn’t. That’s the point I was making earlier. Georgia doesn’t have that lost ‘r’. Well, except maybe just along the coast. Certainly not in north Georgia where Scarlett was supposed to be from. That’s just another example of a horrible fake Southern accent. Put it this way: Holly Hunter grew up just outside Atlanta. Her accent is what Scarlett’s should have sounded like.
Thanks for the pronunciation guides. That will be *extremely *helpful. Any more general guidelines, y’all?
hmmm, I will defer to you since I am only going by people I have met, apparently they are the exception rather than the rule.