So what's this '71 Demon worth?

As I noted in my other thread, I'm looking at a '71 Dodge Demon to add to my Mopar Garage. I'm much more knowledgeable on the E Body cars than the A Bodies, so I'm hoping you guys can help me out.

So, as mentioned in my other thread, this an original 6-cylinder car that's been turned into a 340 clone. It has the dual hood scoops, the wing on the back. It has a black vinyl top, rallye wheels. It's yellow with the black stripe down the sides.

It has a black interior, column shift, etc.

Even though it's badged as a 340 car, it actually has a 318 under the hood (however the guy is throwing in a "freshened" 340 that came out of a Demon in the deal)

Also, it has new dual exhaust, a "new" 3.91 sure grip rear end, 8 3/4 rearend that also supposedly came out of a Demon.

The interior is clean.

I'll try to post some pics later, but for the sake of the discussion let's make a few assumptions.

The interior has no tears in the seats, cracks in the dash, tears in the headliner, etc. Carpet is in good shape, etc.

The exterior is solid, no rust, solid wheel wells, quarters, the floorpans are solid, no rust underneath, etc.

The paint is solid, it looks "pretty good" but definitely not great. I would be looking to paint it anyway.

The guy is asking $15,000, however when I value this on NADA it comes in at around $12,500 (far less on Hagerty, but I usually find that Hagerty always low-balls).

I realize you guys would be offering very rough approximations given there are no pictures, but I'd rather have that from people who are very familiar with these cars.

Thanks!!