Got this'94 6 years ago for parts and have put 65k on it DD ever since. It has a few rust problems but not the end of the world for mechanical repairs. In the rust belt it never stops. Scale, sand, wire wheel, sand, treat all you can, - keep up with it annually- fluid film type product, It...
I'd focus on that Rocker/door area repair and work my way out on structural, then repairs , rust then pm. cosmetics last. fwiw don't consider rust cosmetic. .