So Don asked (via PM) about engine-mounting and I since I think there are several others that would also be interested I will post my method here.

Basically, I tried to be too clever! If you go back to one of my first posts about this plane, I said something about wanting to mount the engine so that: (a) the cylinder didn't protrude "too much" from the cowl, (b) the muffler didn't hang out the side, and, related to this, (c) I could remove the cowl without taking the muffler off the engine. So I mounted the engine "tilted" with the idea that the cylinder would not stick-out the side of the cowling and the muffler would exit the bottom (although not exactly in the center). It looks something like this: