If you haven't already mounted the engine, why not try a Super Tigre 51 or 45?

The exhaust stack allows you to rotate the muffler so it should clear the fuse side. It also allows the muffler to be situated farther away from the engine than most others.

That, plus the Super Tigre is probably a much better engine than the LA40.

Hey, if you're gonna spend the time to scratch build a plane, don't scrimp on the powerplant.

my $.02

Albert