On max-width front wheels & tires on unflaired '71-'75 Panteras:
First, some (maybe most) Panteras are slightly asymmetric: the front suspension construction may cause a right side wheel to protrude as much as an inch outside the fender, while the same wheel will be slightly INSIDE the left fender. This is also influenced by what shocks and springs the car has, whether the OEM DOT headlight-height spacers are in place or have been removed, whether the car normally carries a passenger and/or 100 lbs of cargo -e.g- the ride height has been altered, plus your driving habits: do you make sharp turns at moderate speeds as in autocross, or are you more of an around-town driver?
If you routinely use the car's top end capabilties (150-170 mph), it's recommended to add roughly twice the max-possible caster in the front suspension for stability. This pulls both tire tops backward as much as 1/2", which changes all the above contact points- some for the better, some worse.
So do not buy any wheel unless you get return privileges if it doesn't fit your particular Pantera and you're not willing to make a little clearance in a number of areas. Normally, mounting a tire voids the return possibilities of any wheel, even if the car never rolls a ft, on it.
Second- in tight turns, expect to slightly modify any Pantera in which you add max-width front tires. With 10-1/2" wide tread tires (245-50x XX), in tight turns, the main contact points are:
*the center 14" of both fender's outside lips need rolling under, per factory recommendations in '74
*the front inner fender panels near the bottom of the panel, by the radiator base
*the cowl drainpipes
*the center rear of the inner fender near the brake hose mounts
*the right side windshield-wiper shield
All the above can be done simply, at home, with ball-peen hammers, sections of pipe to pound on for nice neat cavities, and some marking materials. Also, after doing this, the brake hoses may need re-angling to miss rubbing on wider tire walls. Some Panteras have had a few, or all the above mods. But substantially changing wheel alignments or tire brands/sizes may mean another round of tire rubbing and changes. Of course, one can always go for a little less than max-width front tires....