You need a different prop anyway. I use 14 X 8 or 15 X 6 on all of my saito 100's. The 14 X 6 is perfect for the .91, but you need more prop on that 100 to keep it from unloading too much in the air.

Having said that, it won't help your spinner situation. The MAS blades are probably thinner at the root, so they may fit the spinner with less modification.