The G90 glow is a decent engine in its class, but a gas conversion is not going to have the same power as glow. There are planes designed around the YS110 that would fill the bill (Showtime 90, Quest, Venus II), but I have to think the BME gas 90 would be a disappointment power-wise.

My latest artistic aerobatic toy is the Reactor, which I see is now out in a 50 cc size. If you put the Reactor on low rates, it would fly pattern maneuvers, maybe not with competition-level precision but close enough to get the feel of things.

IIRC Dick Hanson was very high on the Showtime 90 with Evolution/MVVS 26 cc gas power. I like the Showtime for breaking into pattern, and I believe Eric Henderson spoke well of it in his column. If you get the stock tuned short pipe I think you'd have all the power you might want. Muffled 26 cc ... maybe, but I would want the power boost of a tuned exhaust.