I have my brace figured out, which is also going to serve as my spacer for my battery tray along with my esc tray, so i should be good there as i am going to be using the idea of aluminum angle running most of the length of the chassis so that should stiffen it up quite a bit.
The only thing i am worried about is the big gap that has been dremeled out by the other idiot, the brace will run directly across the gap so it shouldn't be that big of a deal...
When its done its should have an extremely clean look to it,
i may not even need the 4link brace setup.
Does anyone know how to fill excessive gaps in a chassis?

That would clean the bottom up.
I was thinking J.B. weld but am not sure on how to fill the gap with it unless i put a thin aluminum plate on the top of the chassis to give it something to ad-hear too.