Here is the firewall epoxied to the fuse. Getting the motor mounts into the correct position was a lot easier that I thought it would be. I temporarily attached the mounts to the engine (O.S. 52 Surpass), temporarily attached the firewall to the engine & mounts, then used triangles to position the whole assembly over the plans until the crankshaft was exactly centered on the plans in two dimensions. I marked the mounts' position on the firewall, and drilled and attached them. Sounds more complicated then it was.

Here is the framed-up fuselage...