68 slant six trans to 64 225 slant six

I put a 72 Dart drivetrain in my 65 Barracuda. I shortened the driveshaft about 3 inches since the Dart was a longer wheelbase. I also changed oil pans and installed a B&M shifter that fit in the console. If you want to stick with the original trans one of the trans vendors makes a bushing to fit the early convertor to the later crank.
cant squeeze a "too big" converter snout to fit a "too small" crank pilot. can't go late trans to early crank. (I did prove that out the "hard way" back when I had my 80 Aspen... had gotten a free '63 225 and went to put it in in front of the 80 trans and no go....