Thanks for the help, I went out and got some of the milled fiberglass and I will definitely be putting that on the firewall inside and out. I might even put some on the wing joint after I epoxy for added strength. dgrant, I brought the directions in to work with me today to reply to your engine mounting question. I'm not sure I understand the question but I'll copy into the forum what they put in the directions:

Installed engine position 118mm/4.65in. from firewall to the thrust washer, but I think this is for the presumed .40 or .46 size engine. I have always used oversized engines and mounted them closer to the firewall for a better cg.