TTAM, its not just the OD of the tire but also the section & tread width that needs checking. About 9.5" wide tread widths can be accommodated under stock front fenders. But to do this along with removing the spring spacers AND pulling the wheels back for additional caster (always a good thing on high speed cars), there probably will be light contact in a variety of areas. First will be the wheel arches- the fender lips MUST be rolled under. Next is when turning left or right at full-lock, the edge of the tread may contact the left cowl drainpipe; make it oval with a big hammer in the required area. The tread may also touch the inner fender panel behind the brake hose bracket; again, a shallow pounded- recess will be needed. On the right side, the wiper shield may contact the tread in turns; remove and reshape; one vendor has reworked shields in which the peak has been cut away and a flat area substituted, to ease this mod. Finally, with slightly lowered cars, there may be contact at the extreme lower edges of the inner front fender near the radiator support bracket.
Not all these areas in all narrow-body Panteras will normally be needed, but they might- be ready. Our '72 L had all the above in contact. As a last mod, check very carefully the clearances between the flexible brake hoses and front tread edges; on some lowered, caster-increased Panteras, the right flex hose gets uncomfortably close or touches. Wearing through the rubber line could really spoil your day! And if you've replaced the stock lines with stainless steel, the tough ss line jacket will shave expensive rubber off the inner edge of the tire.
Running a max-width front tire as above frees up options for a larger width REAR tire along with decent handling. Running less than 9.5"-width fronts AND 335-width rears will INCREASE understeer that probably cannot be otherwise adjusted out with different swaybars or coil-over shocks. Or, you can go slow and handling issues will not show up. In back, selecting a 26-1/2"-26-3/4" OD tire will allow the stock speedo and odometer to work accurately.
Lots of things to consider when you attempt to improve on what Dallara gave us in 1970.