A 14 or 16 tooth pinion will work ok with the 4600 or 5700 maybe......You'll need a 3 or 4 tooth pinion for that 7700.
The B44 eats motors. The 7700 is just wrong for that car. My 6900 ended up being a bad match as well. Try a Tekin, Murf, or Trinity 6.5 instead.
Is it the MMpro or the older MM Esc?