It should fit, but something somewhere like the holes for the hinges or latches might be slightly off. As far as repairing your lower box, I patched several holes in mine from where the rear speaker pods & wiring holes were. What I did was I used some mesh drywall tape & adhered it over the holes from the inside with abs plastic repair. I then filled the holes from the outside with the abs plastic repair & ulitmately smoothed them out with lightweight body filler. Just a warning though, any excess of the abs repair is really really tough to smooth out. I had to use a da sander with 80 grit paper on it just to get them smooth enough to use body filler over them.
Lil Chief