Hi
I can advise you about the props. We do need your propshaft dia though. For your size boat with a ungeared car motor, props from 31mm to 35mm can work. The most used metal prop for this would be a Octura X432. It has a 1/8" drilled hub. A Octura plastic X431 is also good and cheap too. Its good your wires unsoldered form the motor. That likely saved it from burning out the frist two min. you ran it. Also you are overvolting the motor. I will not last long that way.
n.h.schmidt