Ballpark Value

It’s a 68 GT Conv cloned into a GTS.

Look at the prices of 68 GT conv. Most of them have upgraded motors from starting life as a /6 or 273-2bbl.

look around here and see how many people have GTS/Swinger hood on their non GTS/swinger 67-69 Darts. Many even have the hoods on 67’s.

Another than than the hood, you add exterior emblems and door panel emblems and that will clone a 68 GT into a GTS after you remove the GT side molding. And then the drivetrain changes as necessary.