I think it is issue #4 of VMX magazine that has such Huskyha conversion, theres room to burn in the frame so shouldn't be a drama.
The only comment I would make is that the motor needs to be at the correct angle to the front frame rail, they look weird if they are sitting in the frame at a funny angle.
Personally I like the TT500 motor in the RM400 N/T frame. Fits like a cock in a sock.