I just sold an 80 Cordoba LS that I have had for ~14 years. About the only place I found w/ other F,M,J-body guys is www.mopowerstyle.com
(formerly MoparStyle). They tend to lean towards the later stuff over there. If you have any more specific questions about J-bodies...I Might be able to help. I had wrecked my 81, and then I completely tore apart and rebuilt my 80 from the best parts of both cars.