Welcome to the 'Bolt!
Not sure I can really help you on the Hydro, but there are a few on here familar with them that might be able to.
On the brake parts, shoes are available, as are wheel cylinders. Hardware and drums might be a different issue, Napa might be the best place to check.
There is one question that will come up, so I'm going to ask; do you have a First Series or Second Series '55? I ask as there are 2 different body style '55s, and they are very different from each other. This can make a difference on the parts.
