manual to auto swap what will work?

It won't be a direct swap, as the size of the hole in the torque converter changed sizes in the late sixties. (don't remember if it went bigger or smaller) You can use a bushing to take up the slack assuming it went bigger. Someone can give you the exact details, but this is just letting you konw that it wouldn't be a direct swap.

This of course assumes that your engine is from 65 as well.