Original calipers on 3C are designated Brembo P2F08 (same front and rear on 3CL). I don't remember the piston diameter. 38mm comes to mind but don't quote me on that.
They come in a few variants - single bleed screw, twin bleed screw, threaded or un-threaded mounting lugs, left or right hand, but none of that matters for buying new seal kits. They all have the same hydraulic components. The 08 designation is all the info you need to get the correct seals.
Just google "Brembo 08 caliper rebuild kit" and you'll find what you need, which is one kit for each caliper. There are several suppliers in Australia. The kits come with new pistons that have what looks like a teflon coating, new piston seals, outer dust seals, a small o-ring and a little sachet of assembly grease. The little o-ring goes between the caliper halves. Some kits also have new socket head bolts that hold the two caliper halves together, and new pad locating pins and springs. I'd suggest you go for a kit that has the lot. That way you end up with a caliper as good as new. Actually it'll be better than new because the new slippery coated pistons are better than the old un-coated type.
Kits don't normally come with new bleed screws (one or two as the case may be) so be gentle getting them out as you'll need to re-use them. They're hollow and can break quite easily if you're heavy-handed. A bit of heat will help if they're stuck. Once the caliper is stripped down to its bare halves you can use a propane torch to heat it because there's no rubber components to catch fire. Don't go too berserk with the heat though. A melted caliper would certainly get the bleed screw out, but it wouldn't be an ideal outcome.
Sometimes it's difficult to get the original steel pistons out of the calipers because they rust and seize in their bores. I've found compressed air helpful, and occasionally a bit of heat too. Just wrap a rag around the caliper half before blowing the piston out with compressed air so it doesn't hit you in the face like a champagne cork. Some mechanics recommend pumping stuck calipers out with a grease gun, but I've never had a suitable fitting to attach a grease hose to a caliper.
