Here's my two cents: Go with the narrower tire combination. I think it's been said here before that a tire on the rear that's too wide can throw the balance of the car off and cause significant detrement to handling. So, I think there's two paths you can choose for a stock narrow-bodied car:
1. Wide rear tires (the 325's or 335's) and standard 225, 235, or even 245 front tires. The combination seems to be well liked and is offered by many of the vendors. However, it probably doesn't "balance" the narrow-bodied, mostly stock-suspensioned car for the track and is really meant for the street. If you had a wider front tire with a wide-body or flared car, then that's different. If you have significant modifications to the suspension to bring it into modern theory and design, then that's different as well.
2. Reasonably wide rear tires with the standard 225, 235, or 245 front tires. We're talking the size George mentioned, and maybe up to 305 tires. Jack (Bosswrench) and others will probably agree that this combination seems to be the better choice for the track for the Pantera. However, street use will be great and the car was never meant to be a drag racer in my opinion. You can't compare a 40-year-old car to newer car technology, so saying that a certain modern supercar uses a certain combination, well, fine, but that might not be relevant to the Pantera with a stock narrow body and mostly stock suspension.
Seems to be kind of a paradox- if you want better track performance in a stock narrow-bodied car, don't put the widest things you can find on the rear and throw the balance off. If you want to impress and don't mind the reduction in handling, then go with the wider rear tires. I agree with the wisdom to find a popular tire size since it's less likely to be removed from production. I think the choice in rim size is important, too. Too much of a good thing can be bad. I also agree/think for the Pantera that won't be driven much in the rain or snow, the summer tires are probably the wise choice.