Love the fastech, fun little boat. Sounds like a fun project, I think the hardest part might be fabricating the motor mount. Make sure the motor is compatible with the drive line, flex cable? Re rout the water plumbing for the esc. Remove the throttle servo from the receiver and plug in the esc, pay attention to polarity.  Might be a good time to upgrade from the original radio and receiver if you haven't already. Might have to experiment with battery location and prop for the proper ride. I'm sure I have left out some important details, maybe a more experienced boat builder will chime in. Good luck.