How long is the piece of string......

If it really is rust free and has some good stuff like GTS dash or WB Caprice front, good interior and wheels etc.

350 may not really add any value unless you are desperate for one with a 350 I suppose.

I will say $10000 to $15000 for a real mickey mouse one with nothing needing doing to it, $5000 to $10000 for a rough one with rust bubbles and needing work to make it nice, and anything rougher than that its only worth the value of the engine conversion and other parts.

Waiting for the limb I went out on to snap off........