rebuilding E-brake calipers

[bddcustoms]

Hey,

I'm swapping in rear disc brakes onto my 1969 C20 with an HO52 rear end using a kit for 14-bolts I got from DIY4X. I need to rebuild the salvaged calipers I'll be using (from a 1976 Caddy Eldo). I've heard horror stories about guys accidentally rotating the e-brake arm, forcing the caliper piston and spring out of the bore, with no hope of it going back in. Anybody here ever rebuilt one of these before? Any advice? For example, if I don't move the arm, can't I simply use compressed air to blow out the piston, and replace the seal, etc. like any other caliper?

thanks!

David