All, I appreciate al the feedback and comments. Some of the things pointed out were things I haven't considered yet and have given me much more food for thought.
I'll try and explain my thought process and interest in the car for those who are saying to "just buy a project car and do it yourself" or stating that the car for sale isn't worth more than $7,500. I'm in my mid-thirties with a young family (toddlers). I simply don't have the time or financial ability to do a project car of my own in the foreseeable future. I've had my El Camino since I was 15 and while it's mechanically sound, it is in desperate need of a repaint and new interior to make it what I want. I'm not trying to make anything show car worthy, but would like to have a car that I enjoy cruising in and is in decent enough condition to take to local cars & coffee gatherings. I would easily need to dump another $10k or more into my El Camino to get it to a state I'd be happy enough with it. Out here in California, just the paint and interior work that was done to this Dart was easily more than $7,500 (unless you have the ability to do this work yourself).
On the other hand, even in its condition, I think I could probably sell my El Camino for ~$10-12K given comparable ones I've seen for sale locally in the last year. So my original idea was that I could swap vehicles to one that is nearly done for a net investment of only a few thousand bucks more. Yes, there are some clear red flags with this Dart. It was obviously always planned to be a flip job by the seller given that he openly stated this in his ad. As of right now, I have no way of knowing if it actually had decent body/paint work done to it or if it was painted in his garage with a HF gun and implement paint from Tractor Supply. Unless the seller can provide receipts, I can only go by what he tells me and see how it looks in person. As to the styling of the car, I get that the seller made some interesting choices that veer far from OEM. Style is subjective and honestly I like some of the things the seller did to this car better than if it were restored to original design. The mechanical unknowns is what bothers me the most with this car. I agree with the comments that this seller looks to be an active car flipper. So I wouldn't be surprised if some shoddy works been done and I don't buy the "just need linkages adjusted" excuse for the transmission.
The Dart is a little over an hour away from me so I'm not sure yet if I'm even going to pull the trigger to go check it out. I'll be giving it more thought going into the weekend.