If you have $500 and a place to put it, buy that sucker like the earth was about to end in 2 weeks!
Personally, I could come up with the $500 but that would mean it would have to sit for a few weeks until a competent mechanic could look at it (and I could pay him to do so). No matter what he tells you the cost would be, you've got it! Running great (and good floorpans) could sell for $3,000 to $5,000 (you didn't say where you were). Heck! If your close to Delaware I'LL come get it!