Auto to Manual? (Sort of)

Hey all, I'm in the process of swapping my blown up 170 slant six to a 225 slant six. The issue I'm having is that the old engine paired to a three speed manual transmission, while my new engine was bolted to an automatic. I'm planning on hooking the new engine up to my manual transmission. Is there a way to swap the flex plate out for the flywheel/clutch setup that was on the old engine?
new engine.jpg View attachment 1715896807

old engine.jpg