Just before you take em to pieces are you happy about putting them back together properly?
There's a very large spring in there that doesnt like blast media of any sort.
Are you leaving the handbrake mechanism in there? You taking it out, you go the long circlip pliers?
Might I sincerely suggest you get on the bay and buy yourself a rear caliper from a Mk4 1.9 SDI and have a practise
You got seal kits? You got piston seals?
Sorry to sound like a tw@t but they're abut four times as involved as fronts and have double the amount of elephant traps as the fronts too and you only find out when fluid is pissing out all over your lovely fresh powder coat.
That said PM me and I'll help all I can, here's some I delivered just yesterday