Ok, little update here. Had some time so I figured out the brake servo mount, and would have cut it to length but the "tires" on my bandsaw have dry rotted, so I had to order new ones.
So I removed the center drive and the other parts and found a nice piece of al, 2/10ths of an inch thick, to use as a combined brace, motor mount etc. Motor will mount to this piece from the underside, as will the brake servo mount and the rear of the battery tray. Will thread holes in it so it can be held to the chassis from the underside thru the stock chassis holes.
Plus the front and rear chassis braces will mount thru it, and it will stiffen the center of the chassis, and help keep the gears mesh correctly. The gear mesh will be set with the center drive and the motor mounted to the plate off the vehicle and then the whole assy will be mounted in. I could cut some "windows" in the stock chassis, kinda like a nitro chassis, just depends.
Heres a couple of pics, had more but the stupid "smart phone" did not save them correctly...
