my tt conversion

hello i m french and i try to convert my new buggy
my tt is back today,
i have any cells gp 3300 and ib3800
i have any speed control, 100, 115 and 125amp
i dont have my motor yet because it s my probleme, i m not reely sure with 7xl or 9l
i m going to run with 12cells max
can you explain me the difference with this 2 motors, i dont like to have a missile, i just like to can run with 1/8 therm with similary perf and good run time
thanks