I think it's coming back to me now.

The firewall is 90* to the fuse. The tank box and wooden beam motor mounts attach to the fire wall at the angle dictated by the tank box, which gives the thrust offset. No modifications to the front of the fuse are necessary. I remember that much!

Always kinda wanted to put a four stroke in mine. But it flys so well with the ST 40 that I've resisted the temptation.

Covered it with linen colored Solartex. No wrinkles after seven years!