dpcrum, welcome to the board. Do you have the fender tag or build sheet that we could decode. If it was a 318, then chances are that it was a plain jain (non-RT). However, those can be desirable, especially in a 70 because people feel (morally) free to clone into anything. 70's and 71's are usually higher in price than the later ones.
If you could share the fender tag info and maybe snap a picture of what you feel are the "bad" spots on the body, I'm sure we could give you a pretty good estimate. However, as many have said on this forum...it's worth whatever someone is willing to pay for it. You'll probably get more money for it on eBay than a private sale, though.