Did a bit of prep work on the calipers tonight. Broke them down ready for cleaning at the weekend:
They're pretty cruddy, like I said earlier
I made up a handy tool for popping out the pots from the calipers - it's a bit of air line with a couple of fittings that I had in my spares box
The air line is screwed into the brake pipe port on the caliper, and the caliper is put inside a container so that when the pot comes out, it doesn't shoot across the room!
A short burst of compressed air, et voila! one pot removed with the minimum of fuss.
After removing the pot, I removed the old seals and the rusty old bleed nipples.
So now I have four piles of cruddy parts that should, after the weekend, be gleaming refurbed calipers. The pots don't seem to be in bad nick - the cylinders & pots are rust free, so they shouldn't go tearing the new seals once they're in.
All I have to do is clean the buggers!