While I can't comment directly on the O-320, here's some comparative info that may be of help. I own a Wagabond (Traveler version) that I bought from the builder nearly 4 years ago and have flown it for about 400 hours. It has an O-235-L2C engine from a C-152 and a lightweight Sensenich wooden prop pitched for takeoff/climb. The gross weight was set at 1320 lbs by the builder to keep it within LSA standards instead of the published 1450 lbs. At 1320 gross, the performance is pretty good, 450' takeoff roll, about 600-700 FPM climb and 90 KT cruise. Although the engine is mounted pretty close to the firewall, I push the forward CG limit solo despite a lightweight alternator and starter. I keep a small tool box in the baggage compartment when solo to make 3-point landings easier to attain . The extra weight of the O-320 may make it tough to get the airframe in the proper CG range.