68 slant six trans to 64 225 slant six
Wont work, easiest way is to get a 68 and up slant six.
Or you if you have another 68 and up (pre Cast crank) you can swap it into your motor to mate them together, its some work but yeah.
Then you can run a B and M shifter or any universal floor mount shifter eliminate the Ball and trunion drive shaft at the same time.
You're all over the place.
1) We don't know what car the OP is working on.
2) We don't know for sure if this is a proposed engine swap, or trans swap.
3) IF it's engine, the crank can be machined to the larger hub dia., or as You stated...swapped.crank or engine.
4) IF it's trans, then You'd have to do one of the above AND change shift mechanisms, driveshaft, put extra holes in the floor. Why?
5) Who wants a cool PB auto car with a Starshifter on the floor? Unless You're actually racing it....
6) Charrlie_S had a guy building later converters w/the small hub, but I believe that source stopped.
7) The OP hasn't chimed in since the original post, so We're puking speculative suggestions at this point.......the original question was answered,......NO.
