Whats the best .18 engine i could put in my rc10gt

I was going to put a .21 or a .26 because i found a conversion kit and i saved up but now i think i don't need that much power so i have decided to get a .18
that will go straight into my rc10gt without to much modifications or none!

well pick an engine that has a short shaft and you can slap it right in. Try os, you can always cut the shaft down to size if you need to.

epic big bores i think have short shafts