DeTomaso used the 'GTS' designation for a 'standard' narrow body Pantera starting in 1971, so don't go to too much effort/expense to verify this. Joules is right on the tie-wraps: they move a little while driving and copper rad tubes are only 0.020" wall thickness. So the hard plastic cuts thru the tubes in short order, destroying the rad. Aluminum rad tubes are 3X wider so work better at cooling and are a little thicker but are not immune from tie-wrap damage.
On shrouds for sucker fans, they help a lot at lower speeds and all are aftermarket so you can modify them w/no effect on originality. Some Hondas had triangular rubber flaps on the engine side of their sucker-fan shrouds, arranged so incoming air pressure blew them open at higher speeds, and gravity held them closed around town. If they have junkyards (breakers yards) in your area, find them there, or copy the design from scratch. Bigger will be better but there's only so much available area on plastic fan shrouds.
Wheel alignment and tire sizes make a huge difference in handling. There are as many opinions on what works best as there are Panteras, so some experimentation is in order for your personal machine. Good luck & welcome!