Have any of you guys flown the old Sig Skybolt? I recently acquired one that is already framed up but the engine that came with it is an antique O.S. that I believe was made in the late 60's. The Sig version of the Skybold is a little smaller than the GP version but it does call for a .60 size engine. Any idea how big of an engine the old Sig will handle? These bipes sure are beautiful. I'm tempted to pick up the GP version for a winter project.