Re: what did you do to your motorized bicycle today?
Your build is looking good. With just the motor mounted in-frame, your bike wouldn't be too top-heavy at all. But with those beastly ammo cans and a gallon and a half tank on the top tube, I can see why you're trying to lower things.
Are you still running a 27" rim in back? I kept my original hub, but used quality stainless spokes to lace in a new 700c rim. The diameter is only 8mm smaller so there's no problem with the brake shoes reaching the rim. The smaller rim gives more frame clearance to use fatter tires, which you ain't gonna find in 27". I fit up to 40mm tires now, and might go a little fatter if I mess with the frame a bit.
Still has all the benefits of "skinny-tire".