Same guy with the Super Extra has the 50% and 342. Don't go with the 342. There are considerable exhaust design issues with fitting the engine. You cannot, make that absolutely cannot, rotate the cylinders to reposition the carb and have the exhaust ports on the other side. The initiation of the boost ports are part of the case casting and rotating the heads cuts the heads off from the boost ports. The carb and intake manifold are massive, and although eliminating the intake manifold is possible using a 3w mounting plate, the carb still projects a considerable distance from the engine. Something is going to stick out that you don't want to stick out, somewhere. If I had it to do over I would wait for the MVVS. If you speak with Bill he'll tell you the plane was designed around the 275, and the later planes are lighter than the first release.

I did some of the horse stuff when the kids were still home. Darn things were accidents looking for a place to happen. Gave up on studding since their legs were so long and they ran too fast

Draganov Reach out and touch whatever.