If there are rusted out areas on your inner-to-outer cowl part, Do Not Get Rid Of It. You will be many hours ahead of the game to cut out the rusty parts and weld in new metal, than to try to make the aftermarket ones which are welded together and aren't anywhere near usable out of the box.

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission