this motor and a mm
 

http://www.hobbycity.com/hobbycity/s...idProduct=4937
as the title with 4 or 5 cell a123?

If geared to keep the MM's temp in check and with a fan on the MM, it could work. However, I would bet that gearing would result in the motor being undergeared. That motor could draw a lot of current. I think those KB45XL motors are better with HV due to their higher power rating. (UH rates that motor at 3500+watts, and 5s2p A123 is capable of 2000watts peak, so at 2500watts that motor would require something like 250amps!)

how many amps do you think it would pull?

It's virtually impossible to know without measuring it. There are so many factors involved with that, including terrain, tires, gearing, driving style, capability of batteries/temp of batteries, ESC settings, drivetrain smoothness, etc. (BrianG's opinion)

Aside from that, assuming the MM weren't already too hot and the batteries could put out a lot of current, I'd guess it could easily spike to 150amps.