Thanks, Myron.
I gotta say that my only mechanical experience previous to my presently busted bike is changing brakes/alternators/starter/waterpump/ on a car. (And adjusting the fuel mix and timing on one very old chevy.)
I've haven't seen a Tanaka or Honda engine, or a Grubee mount, except online, but what you're saying is that I can pretty much put anything in my frame that'll fit in there?
I suppose I'm also limited by the two clutch sizes (50-something and 70-something mm) and/or the drive shaft widths? This will be my first time to delve into those parts of an engine....
Tom