I think for my purposes (30-50 mph tooling around our curving New England blacktop roads), any functioning engine would be fine with me.
A colorful description of the Twin Cam, from a Time magazine article awhile back:
"It was a leaking, piston-burning, plug-fouling nightmare of a motor that required absolute devotion to things like ignition timing, fuel octane and rpm limits, less the whole shebang vomit connecting rods and oil all over the road. Many years after the engine was taken out of service, it was discovered that the problem lay in the carburetors. At certain rpm, resonant frequencies would cause the fuel mixture to froth, leaning out the fuel and burning the pistons. I've never had any such trouble with my iron-block, pushrod, lawn tractor engine. I'm just saying."
Just sayin'