Thanks for all the information, gentlemen!
Attached are images of the back end of my 318, obviously just arrived and not cleaned up. The block number is 2468320, which seems to make it a 318A small block from '64 - '66 with 1.84/1.56 valves. The mating transmission was manual.
Taking heed of your caveats vis-a-vis the push-button cables, etc., I'm now much more inclined to go for a floor shift automatic, with presumably a 904LA. I'm obviously going to need a starter motor as well.