any year, SMALL block 67 and up 727 will work. just get a neutral balance flexplate. If you're gonna go 4 speed route, 833s aren't too bad to find price wise will vary. You can get bellhousings easily as well.
What is the purpose of your car? if its a daily or a cruiser, you might think about going A518, which is essentially the 727 with a 4th gear OD. Just wire the OD to a switch when you want to go OD
