I built a Nosen Gere Sport bipe and I read that even though it too was for a 60-90 guys were putting G-62 in them. One guy put a 6.4 twin in his!
I'm leaning towards the 40cc engine. I'll put the servos in the tail to assist in balancing and I'll re-enforce the firewall and will use isomounts to lessen engine vibrations. What do you think? Let me know as I'm still working on the wings. Thanks.