You mentioned 327s in your og post, Mine had the swap to a 327 back in 1969. I replaced it with a new one last year. I found a rebuilt 327 with a mild cam and a 100k warranty for $1600 or thereabouts. Mine has a 3 on the tree and an overdrive. I would think going with a rebuilt set up like mine would be cheaper and less work than a modern automatic with overdrive. BTW all that new power and high speed cruising ability, well you better have a real tight and ship shape front end and steering or it will always be an interesting time on the highway at 70. So more money there. Maybe it's just me, but a nice clean 327 just looks right in an old truck.
