My guess is the subframe bushings are beat, and maybe the frame mounts on the frame. The question is how much of a pita is it gonna be to get them out. putting the frame back in is not too hard.
Here is what one of my frame mounts was like:
<--rusted
<--new plate welded in
<--the small hole is used to realign the frame
<--painted & ready w/solid mounts
a lot of info:
http://www.nastyz28.com/forum/showthread.php?t=17406
I have had no issue with paint on my frame next to headers - por-15, misted with etch primer, rustoleum semi-gloss black topcoat.