My rough guess is that the diaphragm and seals in your regulator are at least 40 years old. I certainly wouldn't trust a rubber like material that old not to leak a flammable gas. It is a standard procedure to have regulators serviced and in the process replace those parts so it will work like new again. My recommendation here is to work directly with whoever can service the regulators instead of going through a middle man. I took my regulators to my local welding supply store and the final price was double because of course they make money on the transaction too. There will be posters on frame building forums that can suggest places to get this done.

Your torch seems like it was designed primarily as a small version cutting torch. Someone might be looking for such a torch handle because of its size and might be willing to pay considerably more than what you paid for it. For example older Meco torch handles (not to be confused with the modern ones now made Victor) are prized for their light weight, semi flat shape and knob placement. They sell for a decent price. Perhaps the Harris model 11 torch handle has some followers looking for them?