If the caliper piston boots are not torn or have cracks in the rubber, then they should be fine.
Avoid brake cleaner etc, on the rubber, sure spray it all but don't drown the rubber. Minimize the time any rubber or plastic is exposed to harsh cleaners. That's why brake cleaner is a preferred thing, it evaporates fast so does less harm when spraying around fragile stuff.
For the future, avoid removing the front caliper bolts, only take out the bracket bolts. The caliper bolts have grease in the assembly to the caliper, and removing them exposes the pins(bolts) an grease to air, and dirt. If you just remove the two large caliper bracket bolts, then the pins/grease remain undisturbed, less likely to be contaminated. it's a dirty job and most people aren't perfect, which creates faster wear of the calipers(the pins and bore those go through). Rebuilt calipers are great if the pin bores weren't worn much, but older cores often are.
The rear you have no choice, there are just the two caliper bolts. But those go through sliding pin sleeves that have grease enclosed around them. I to reattach one new boot when putting my rear calipers on.
When you install the rear calipers, go slow. It's easy to put them together, other than the pads are unique left and right. Look at the end notches on the pads, one end has no protruding tip, and the other end has one. The end with the extra tip goes to the bottom, it catches the bottom "foot" of the caliper bracket, and then the caliper rotates up onto the upper foot. The bottom hooks onto the bracket bottom, and the top pivots onto/against the bracket top. There is a SS hardware cover piece that goes onto each part of the caliper bracket. Those are identical, and they sometimes fall off. You can easily put them back, and hold the top one in place as you pivot the caliper up onto it.
When you are there setting a rear caliper onto the bottom bracket "foot", right then stop, look at the two sliding sleeves(the rubber boots on each end). Those want to come outward towards you. Those have to be pushed gently back(inward) enough to clear the caliper bracket(where the bolt threads are). You can usually do that by hand while pivoting the caliper up into place. Look at it a bit before you do it, noting what parts are coming together and have they fit etc. It's not hard at all, but if you didn't see the sleeve/boot being in the way of the threaded hole of the bracket, you might be frustrated the first time. No worries, you'll be fine.
lol.
