ORIGINAL: Toad
The crank from the fuji is probably too hard to cut so you would have to send it out to a grinder. New bushing made for con rod....Have you measured the stroke and bore to see where the displacement will be? hate to see you chase this and not end up with a legal engine.
The norvel .074 crank has been done in these but not in a lower stroked version seeking the .049/.050 displacement
The original crank pin was ground smaller OFF Center to get the smaller stroke. the dia of the pin has nothing to do with the stroke. it is the center of its location.
Do some simple math, figure out what stroke is needed then set the pin offset. maybe the fuji pin will have enough material on it to grind it to a new center.
I hope your grinder doesn't charge you a lot.
A brass bushing at the front end that's a tad shorter will eliminate the need to grind away at the crank. Add a rear bearing and we may just have some serious potential.
IF the Fuji just happens to have a shorter stroke, that would make this all that much easier. How do we find out?