I'm not wanting to add to what has already been written, but I would like to provide some explanation as to why we modify what we do, and at least get you thinking about the choices you have to make.
In no particular order:
Rebuilding whatever is worn out should go without question, right?
The choices in control arm pivots are OEM rubber bushings, new style poly bushings that pivot around an inner sleeve (instead of the old style that pivoted inside the control arms eyelet) or spherical rod ends. I like spherical rod ends, no deflection, no distortion, and ultra-low friction. I think the average owner would most enjoy the OEM rubber bushings, as long as they are new.
To improve the handling you have to lower the car for a lower CG. Period. This requires shocks with adjustable spring "pre-load". The new shocks rerquire new springs. You'll lower the rear until the lower rear control arms are parallel to the ground. Then you'll lower the front until the door jambs are level with the ground. A good set of shocks will modernize the ride of the car too.
Modern gas shocks have far less friction in their operation. The guys selling you your shocks will be specifying higher rate springs than the oem springs. This will improve handling, but since the shocks have significantly less friction the ride quality will not suffer. The overall compliance of the modern shock & spring assemblies will be as good if not better than the oem units.
Ford modified the upper front control arms & reduced caster form the original 6 degrees to about 3 degrees. That's insufficient for good handling or stability. The way to fix this is to have the upper front control arms modified for more caster. The modified urethane bushings do not provide enough caster.
Ford put a smaller rear anti-roll bar on the Pantera to increase understeer. To rectify this requires a larger (Euro-spec) rear anti-roll bar, its about 7/8" OD. There are 1" OD sets (front & rear) available too.
The sperical anti-roll bar ends take a bunch of friction out of the chassis & I consider them a necessity. The stock ends have an insufficient range of motion, they bind & have been known to snap anti-roll bars.
You cannot have state of the art handling riding on the 15" Campy wheels, because there just aren't any good tires available. So you must plan on upgrading the wheels & tires. The lighter a wheel/tire assembly is, the better your suspension will follow irregularities in the road & remain in contact with the road. Maximum traction requires keeping the tire in contact with the road. A light wheel/tire assembly will also allow your car to accelerate faster & brake in shorter distances. So, you want to buy the lightest wheels & best tires your budget can tolerate. The lightest wheels are those 3 piece style wheels. They are also the most expensive.
What size wheels to run depends upon which Pantera you buy & your personal taste in asthetics. Some people just haven't warmed up to the looks of the very narrow sidewalls of today's very low profile tires. The narrow body Panteras have a larger wheel well radius than the wide body Panteras. Asthetics will dictate that you select tires that are approximately the same OD as the OEM tires, so they will look "right" within the wheel wells.
Narrow body Panteras were originally equipped with tires that were ~26.9" OD in the rear and 25" OD in front. The current state of the art in tires for a narrow body Pantera will require a 18" - 20" wheel in back shod with ~285mm tires on 10" wide wheels, or 325mm tires on 12" wide wheels if you must have the ultra-wide look. Up front 17" - 18" wheels shod with 245mm tires on 9" wide wheels. If 285mm rear tires are used the rear wheels can be spaced outwards (less off-set) to increase the rear track and improve the adhesion of the rear end in corners.
The wide body Panteras were orignally equipped with tires that were 24.5" OD in the rear and 23.9" in front. The small OD of these tires makes it a pain finding modern wide tires with a small enough OD to compliment the wheel wells. To fit state of the art tires on a wide body my recommendation is a 19" x 12" wheel in the rear wearing a 315/25ZR19 tire and a 19" x 10" wheel in front wearing a 265/30ZR19 tire. Some owners willing to accept a larger tire OD in the wheel well have chosen wider wheels and tires. Its an asthetic choice.
When it comes time to upgrade the brakes, select rotors that fits inside the wheels. If you want to be able to re-install the 15" Campy wheels at a later date, use 12.19 diameter rotors. Select four piston or six piston calipers to go along with those big rotors. Since these components are attached to the suspension, and the rotors even turn with the wheel/tire assembly, you are going to want to consider the weight of the componets when selecting them. I'll give you one clue, look for the brakes that have the word "Superlight" in their name.
cowboy from hell