Somewhere around 1966 is when Stopmaster brakes were introduced so it may or may not have them. I don't like them, but it is actually easier to put spring brakes on them than on many GM drive axles born with S cam brakes. Many of the GM setups simply don't have enough room got dual chambered brakes.

You really don't need another air tank. Mount a KN20031 valve on the dash. https://www.ryderfleetproducts.com/haldex-kn20031/valve-p-u55-kn20031

Tap into an air supply at the top of your air tank and run a line from it to the supply port of the KN20031 valve.

Run a line from the delivery port of the KN20031 valve to a quick release valve. https://www.ryderfleetproducts.com/haldex-kn32011/quick-release-valve-new-p-u55-kn32011

Mount the quick release in the middle in the rear of the truck. Then run rubber lines from each of the delivery ports to the port in the each of spring brake chambers. There is nothing complicated about air brakes.
People just try make it complicated. If you google Bendix, you can come up with schematics, but you can forget about most of the valves. I am assuming it is a straight truck or is it a truck tractor.