RE: seamaster engine mount from plans?
When I converted my seamaster to electric, I decided to go with the lightest mount I could design, that would also carry some of the strength down to the thicker plywood portion of the pylon. I settled on two pieces of angle aluminum that sandwitched the pylon and provided the 4 bolt points for the motor. On my Lanier mariner, I went with a shorter bracket, as the pylon was strong enough all the way to the end. I think as long as you locktighted them, maybe glued with epoxy, the angle to wood joint would be plenty strong. The long standoffs might be too twisty for a glow motor, but they should be shorter than I used, so they might work. Esp if the plan shows the motor mounted right to the firewall. I have always been more comfortable with metal than wood, so building the transition from vertical pylon to firewall out of wood blocks seemed like un-needed work. Don't know how you want to mount a tank, my seamaster just used two dowels pointing back from the firewall, but they could be attached to the pylon just as easily.