Here's a crazy idea from an ignorant newbie:

Has anyone thought of coupling two conversion engines together to make a twin? It's kinda unusual for gas engines to have shafts protruding from both ends of the crankcase. And since some are precision threaded or tapered, it would seem that they might be able to be linked up by joining the cases and crankshafts with standard precision machinist techniques, carefully done to avoid vibration. A standard mechanical flexible connection could also be utilized. Presumably both would retain their own ignition systems and mags, etc. Perhaps they could be joined 180 degrees out of phase.

Am I nuts or just naive? But this is half the fun, pushing the envelope.

Just thinking of that monsterous 1/2 scale chainsaw powered Mustang with the micro video camera in the cockpit mounted on a servo for 360 degree views of low-level strafing runs...