RE: good engine size
Max:
Two things come to mind immediately; too heavy, and structural failure. And if you strengthen the airframe to allow the heavier and more powerful engine, it will have to go faster just to fly. Going faster could lead to aerodynamic problems.
Why not just use the 1.08?
Bill.
PS: If the 1.60 were the Magnum, the ASP, or OS 1.60 twin it would be well worthwhile. wr.