That's a tough call....
I ..... and this is just me talking.... put a "value" of ~$250 on the title-less 'POS '67 Coupe roller. Basically, the scrap metal value of the car.
The same car.... if it were a 2+2 would probably fetch at least 10 times that amount in the current market. Likely more.
I don't "set" the market value for these cars, it's just the way it is.
Two friends of mine have cars they want me to buy. They're tired of storing them and want to see them finished/on the road in a good home.
One guy has a '67 Fairlane.... 4 door, 100% complete, running and driving 289/C4, just needs paint (it's stored in primer). I wouldn't give him $500 for it and he'd be insulted at my offer. I'm just not interested in his car.
The other guy has a '67 Fairlane, 390/toploader/9" car, 2DR, slantback, original color was Raven Black. No major rust/rot, but it needs a LOT of work. I offered him $3500 and he's still thinking about it.... and has been for the past couple years. I'm VERY interested in his car.
The moral of this little story is the body style makes a BIG difference!