OK so I decided to start my conversion of a HPI Nitro MT1 to a brushed motor and am a little stumped. After I fashioned a motor mount I was looking at my pinion gears and they will not mesh at all with the spur gear due to the teeth being too shallow, and close together. So here's my question anyone know what I can do? are there pinions with thicker teeth that could potentially mesh with a nitro cars spur gear?
I was looking at 1/8th pinions online but I am not sure if there is a difference in the motor shaft sizes on 1/10th or if they are the same.

BTW its going to run my 35t motor that came out of my brama and if that works decent with that might pop in a 20t or a 12t instead.

Any help would be greatly appreciated.