Advice on inside rocker panels and body brace

[kanuck]

Wondering what the best way to fix up my inner panels????

I just got started under my cab today to get it cleaned up and to get it ready for some rust repair.
The great news is the rust is limited to the inner rocker to floor area and the rest of the underside came out better then expected.
The bad is figuring out how to repair whats there with out to much cutting into the good parts.
The cab was painted about 13 years ago and then the truck sat the last 8 years till I got it. It was a 1973 Cheyenne 3/4 ton 4x4 with a rotted frame, so all I kept was the cab, hood, doors, and a fairly nice grille assembly.

When it was painted the outer rockers were replaced and possibly the cab corners with new GM pieces, but it looks like all the inside pieces are original to the truck. As the following pictures show, the rockers are still in great shape, but where they were attached is having problems along with there being not much left of the inner panels. Also the cab support on both sides are rotted on the bottom.
The rest of the floor was under coated and after scraping, most of it still has it's original paint in great shape.
Check the pictures.....