Don't forget the oil pump, water pump, and ignition sensors/distributor, etc. if you really want to reverse your engine.
I suspect that these will require much more than a drop in replacement, (like re-engineering the fluid passages in the block) or would you just find a way to make these devices turn the right direction?
Might just be easier to either use an opposite propeller and live with it, or find a different re-drive if necessary. Those using a planetary gear tend to reverse the propeller anyway.