Pros and cons of rebuilding a 1975

[nu2-72]

I have had several mid 70's over the years and all seemed to be prone to massive body rot. Live North of Kansas City, Mo.
I am now looking at a 1975 from a friend who passed of cancer and the body is typical. Since I do not want to drop an arm and a leg, what have you guys learned the hard way?
Better to go to one of the site vendors and get new sheetmetal or find a complete Western donor? The Midwest will have very few original rustfree parts but those I might find would be OEM. How is aftermarket fit and quality?
Sad thing is the price the wife is asking and it needs everything. I mean everything. Cab, bed, fenders, hood. I am thinking a polite no thanks may be in order.