I had one of these years ago. If memory serves, the included motor mount just bolts up to the ply firewall. Not a complicated operation. The firewall is just epoxied to the foam, and is strong enough so you don`t have to worry that the firewall will pull loose. I just mounted my .40 upright as the instructions indicated.

Now flying this little beast can be something else. On grass, when you power up, the plane would always nose over and you get to start all over again. I would just rev up and hold the tail down and and when ready, shove the plane forward for launch. Kind of like launching a F-1 pylon racer. Also, in the air the plane will pitch down and right when you apply right rudder when flying at half + throttle. I`ve heard this is common with all Spits. Count on nose overs on landings and a quick sink rate.