It has been my experience that any motor worth installing is worth rebuilding. As for the year of motor, a stock 350 is a stock 350. The motor has changed so little in the last 30 years that it really doesn't matter. I am doing a similar swap in my 63, but I am using a TH375 tranny because I know that the stock 4 speed would melt under that load, same goes for the stock 3 speed.
