Randyj,
Why you want to rebuild them ?
They leak or just as they are quite old ?
If they leak clean them as better as you can with hot water and brake cleaner.Them inspect the body carefully especially around the piston seals as the corrosion here is usual.If they are okay spray some WD 40 around the bleeders and the x-over pipes and gently try to remove the with a proper tool.If they come out okay.If not spray them again and leave them for some time.If they seems rusty maybe it need to heat them VERY FEW.Also check the x-over pipes for rust.You need 4 dust seals and 4 inner piston seals for each of them.If you bought the parts directly from Porsche you get and the pistons.Replace them anyway.
Here is Mike site Brembo calipers rebuilder expert :
www.prospeedmotosport.com he has all the required parts is very good prices and he can rebuild or exchange your calipers.
Rgds,