So I pull down all my ZZ MT stuff and I realized I already have the PERFECT chassis for this project already built!:
XL-1 (minus the Lego wheelset)
Please see that thread for specs and chassis pics.
I tried to keep the feel of the original ZZ in that I mismatched the wheels.
The body has plenty of clearance for the additional battery pack as well.
I'm still learning my new camera. Sorry about the quality of the shots.
Monster Mater: