Hi Dan,
I think you have enough information, if not just send me a round trip ticket and I'll make a 'house call' .
The original Beetle was powered with the YS short stroke (as was the original Aurora). The YS long stroke came out very late in the '80s (and the AR, not until the early '90s). The YS 60FR responds very well to long pipes and larger props as it has a very flat torque curve. Ivan Kristensen ran the YS 60FR in his Summit series very successfully.
As for grass runways and the Beetle, try an 11x11 or 11x10.
Good Luck!
-Will