1/8th buggy with MM?

i have 2 CEN matrix, one FRE that i race and the other one is a stock model as a spare for parts, Since i don't break to often :) i will convert it to electric, i was thinking to run it on zippy 4s 5000mah with one of my mamba max esc. i was looking for a feigao motor since i'm on a budget for this project (too many r/c's already)
any suggestion for the motor? L or XL
i will use the rc-monster motor mount and not sure about the battery tray... i might make one at home or i'll go with a rc-monster one.
for the ubec, also any suggestion?
Thanks guys!