IS,
I cannot imagine having to send a Girling caliper as used in the Mangusta, to a shop to have rebuilt. There is one rubber piece, the o-ring, seal, retractor (pick one....) and the piston. Both parts are available if you know where to look. If your car has been driven over the years and the fluids replaced at some sort of regular interval, there should be little to no pitting in the pistons. (Pitting in the caliper bore is a non-issue unless you are talking epic erosion...)
If you can safely pop the pistons out using air pressure, and clean all the parts up, there is no reason you shouldn't be able to install two rubber retractors, and two pistons.
I would recommend a tube of brake assembly lube.
Other than this, there really is nothing fancy about a Girling caliper. Basic brakes, not even any dust shields on them!!
Steve
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.