Steve,

Consider a couple of factors. If you complete the Jenny with covering before you make your engine choice, you can get a good idea of how much engine weight will bring it in balance. Why mount a 90 4-stroke AND 2 lbs of lead on the firewall. An 8 ft. span bipe can probably handle a very wide range of engines. For me, I would start with a G-26 Zenoah (I am a gasser).

Second issue is prop diameter. As said before, a 60 2-stroke was the big engine of the day when the Nosen design came out. My guess is it's 12 or 13 in. prop will look all wrong. Back to the G-26, you can mount a 16 or even 18 in. prop and I bet it will look much more appropriate. If you have 2 in. of ground clearance with whichever prop, you have more than enough.

Have fun with it!

Bedford