hi lrt
I have converted two older masport tillers for costumer's with the cheap Honda copy ohv engines.
the mud scrapers for the wheels had to be removed
the rocker cover just clears the wheel.
crank case bolt Patten is the same, you will need new mounting bolts metric m8 x1.25 pitch
if you need more clearance between the wheel and the rocker cover you can pack the engine crank case out a bit from the mounting bracket with some nuts as spacers and longer mounting bolts.
you can pack the motor out quite a lot and the coupling adjusted to cope with this movement
the handle bar brace needs to be modified and new brackets made welded in place
the Chinese Hondas are a tight fit but a good cheap conversion
just make shure any motor you get that the crank shaft size is the same to fit the coupling

cheers2