I have to say De Tomaso are possibly one of the trickiest cars to find tyre fitment for.
Pirelli have made quite a few new tyres that might be of interest to you guys https://www.longstonetyres.co....relli-cinturato.html
They are also making a new tyre 285/40R15 Cinturato P7 which i beleive is a tyre that might be of interest to Pantera people. They do currently make a 225/50R15 P7 and a 205/50R15 P7. Any day now i should have a 345/35R15 P7. https://www.longstonetyres.co....li-cinturato/p7.html
I hope these are useful to you.