RE: Motor Swap
Tower may or may not be able to help you...
Hanson Hobby is on Rt 27 in Hanson, roughly 15-20 minutes east off of Rt 24 from the exit in Brockton. They have a website where you can get the hours they are open most night till 8Pm except Wednesday they close at 6 pm.
Another place you may want to check put is CME hobbies in Plymouth (while they do mostly helicopters) they have a good selection of electric motors.
You may also want to check out a store in New Bedford I believe it is called "Big Boys Toys".
There is also a hobby store done in Hyanis near Macy's although they don't have a big selection of motors and controllers.
One place that does have a good selection of electrics is RC buyers Warehouse in Nashua about 1/2 north of Boston on rt3.
What you are doing should not be all that much of a big deal as far as a motor swap.
If you have had the car open look and follow the leads back to the ESC from the motor.
Is it part of the receiver or a separate component?
If it is not an integral unit with the receiver all you should have to do is swap out the ESC, if it is you will have to swap out the receiver as well.
If you have any background in electronics you could probably get even more creative...