I framed up a lanier ultimate pitts and plannned on using a saito 180. This plane build pretty light, so I think a 300 twin would be over kill, and I am very power hungary! This plane was prolly designed around a 120 size four stroke, so I would think that by putting a 300 twin in it your wing loading would suffer some, you might have balance issues, and the cylinders prolly would stick out the cowl.