Cleaned up with a wire brush/drill.They look brand new did you paint them or have them blasted?
You can either do that, but it will be messy when it dumps all its fluid. Or easier to drop the calipers off and use an airline to blow them out.I watched a vid of a lad taking caliper off a bracket pressing pedal down brake until the piston popped out then he just replaced seal and dust seal.
The eBay kits are all pretty good mate. You should be fine with any of them from a reputable brand.Was going to do them black so no worries there and do you use a certain brand for the seal kit as I just looked on Ebay