Actually all I was suggesting was to check the prices of the Harris parts that are designed to work specifically with propane and also the cost of bringing the regulator up to safety standards. Then compare that cost with stuff that works and see if the difference is worth it to you. The O2 knob in the middle between the other knobs is to make this primarily a cutting torch and is a little weird but otherwise it might work okay for brazing. It isn't terribly expensive to have the acetylene regulator rebuilt with a new diaphragm and seals -probably a lot cheaper than the about $100 for a new propane one. The other question would be if available mixers and tips were truly propane specific. Uniweld for example says their mixer/elbow/tip combination also works with propane even though it is designed for acetylene. This is a true statement but in reality it is just a regular acetylene unit. What they leave out is that even though their regular acetylene mixer/elbow/tips works with propane it does not work as well as those designed specifically for propane. Propane mixers have more and bigger holes than acetylene mixers and propane tips have a recess on the end.

In addition there are some real advantages of using multi-port tips specifically made for propane and the threading on the Harris elbow may not be compatible with any of those tips and it might take a machinist to make some kind of adaptor. I would certainly want to know this before spending money on something that didn't work with multi-port tips. Some people love these challenging adventures to solve a specific problem while others just want to buy something that works well immediately.

There is always a kind of time/money trade off when buying old or used equipment. Is the time spent figuring everything out as well as the risk it may still not work as well worth the savings over buying what will work well right out of the box? Only you know that answer.