I agree it does not need 60hp to fly, but if it is available why not try for it. At 40hp in El Mirage, 3000' plus air density, more is always better.
I hope to find something out this week, 60hp with a 68" prop might not be the same thing as with a 52" prop.
It would be nice to come up with a direct replacement for the Mac, there are a lot of Bensen's out there, but I am afraid it will lose something in the translation, going from the loudest gyro to a almost silent one, might take some getting use to.