Need help with caliper seals seating on a 69 catalina
 

I have a question about installing these caliper seals on a 1969 catalina caliper. I can't figure out how to push this metal ring in to seat in the calliper. I have tired pushing it in with a screwdriver on all sides but it just won't fit. Am I missing the obvious answer or do I need to make a tool to push it in evenly. I have seen a video rebuild a single piston gm caliper but he skipped over the seal installation.

Not many people rebuild callipers anymore, usually cheaper to buy reman units from the part store. The pistons are usually pitted and
require replacement. But in order to change those usually you have to take the piston out and use a driver to install, then with a clean, well lube
piston, gently blow air into the line side of caliber and push the piston back into hole. This can be dangerous to the fingers if using too much air.
Put the piston in tilted to the top side of caliper and the boot will blow up to go over the other side of piston. Easier to buy remans.

Just buy a rebuilt caliper. They are under $30