If you actually drive your car as it was intended, 1/2 degree of rear camber will noticably improve the cornering of the car. The downside is, the inner edges of the rear tires will wear faster than the outer edges. You can enjoy the car more on the road and make the tires last a bit longer by picking up a tire tread depth gauge and keeping track of tread wear, while switching rear tires as the gauge will indicate. On a street Pantera, the right rear tire seems to wear the fastest. A Dremel tool and a mini-metal cutting disc- & some patience- you should be able to cut the washer(s) off once the a-arm is pulled away from the frame the max.
If you do corner 'vigorously', you really should add an aftermarket '10-qt' oil pan such as Aviaid. In fact, most Pantera shops will no longer sell you an engine without such a pan, due to warranty concerns. The capability of a Pantera with modern tires is such that a few spirited drives on curvy roads (or one afternoon track event) is about all it takes to wreck a set of rod bearings, even on a stock Pantera. With a stock pan (3 different possible), at least follow Ford's last recommendation and overfill it to 5 qts plus one in the filter. This will delay the inevitable.