I would still suggest that a strip down before cleaning be advisable.
Same on the calipers.
You need to know what your pistons look like (corrosion) and you probably want to replace the seals.
They require a hefty torque on the two large fasteners holding them together, but that is no big deal.
There is a small o-ring that goes between a passage common to the two halves. This is NOT included in the rebuild kit, for some reason. We have a member here (Mike V) that bought a package of 50 of these small o-rings. He is in California. You should check with him about getting a couple from him or determining the size if you want to look for some locally.
Kit

Ick!

New pistons are hard to find.

If really bad, you may need to have new ones made.
