Thinking of making a new exhaust system for my China girl.

So, I'm thinking of making a new exhaust system for PiZhou, I'm planning on making it out of the existing flange, copper and iron pipe, and on old Bernzomatic propane torch tank. Th header pipe will be copper, and the pipe going into the "expansion chamber" will be the iron pipe, because I think the Bernz. propane tanks have regular 1/2 inch pipe thread on them. And, I'll hold all the pipes together like how they do it on snowmobile exhaust systems. Thoughts, comments?