Got props with an oversize hole for the engine shaft? An old trick is to cut a strip of paper not quite as wide as prop hub thickness. Now start winding this around engine shaft until it brings up the diameter to match the oversize prop hole, and tear off the excess paper. Use the TLAR method---That Looks About Right. Yep, some cut and try is needed. When you have a good fit, remove paper strip from shaft, rewind it so in slips into prop hole. A drop of CA will make it permanent. If the fit is now too tight you can 'ream' it open slightly with the taper of a pencil. Of course you will rebalance, right?

Good luck, Bob G