Piston seize from varnish build-up as well as semi-metallic brake pads rust-bonding to the rotors. If the car moves at all- which you said happened- then at least the rotors are (now) free. Brake calipers can be rebuilt at home, at very low cost and very high labor expended. This is one of the sloppiest jobs one can undertake on a Pantera. If you've seen it done it before, plan on all day to disassemble, clean, reassemble and bleed. If this is the 1st time, it'll take several days-perhaps a week. Also plan on getting filthy.
Basically, one removes each caliper in turn and totally strips it without separating the caliper halves. With varnish-seized pistons, an air compressor or Porta-Power jack may be adapted to force a stuck piston out. Rebuild kits are available from our vendors. Once a caliper is stripped of its pistons, you may find a row of rust pits that CANNOT be resealed, so that piston must be replaced. There are 10.
If you're simply physically not up to the brute force approach or you don't feel lucky, one shop that specializes in rebuilt Girlings (front and rear) is Pantera Parts Connection in Carson City NV. He accepts unbroken stock calipers on an exchange basis. Call or e-mail Larry for info & prices. There is a web site.