Interesting question. I grew up learning to drive with only manual trans. Still lean that way but in getting older, it is easy to appreciate an auto when stuck in traffic. Many years ago, I swapped out a TH350 for an M-22 in a Camaro. Wasn't that hard, actually did everything in the barracks parking lot in one long day. Sue wouldn't try that now but is was worth it then.
I have been thinking of swapping the TH400 currently in my 72 C10. Howver would not go with a 4 speed, probably a 5 or 6 speed. My 69 Vette has the 6 speed out of a Camaro and having the 2 od's is nice. Not that I would want to take the truck to 150+. Not quite that brave...
But it would be nice to take the rear gears to 4.11's and still be able to drive highway speeds.
Not sure an of this rambling helps any, just my preferences...