The Bernzomatic propane cylinder. Find an empty one, look at the 2 minute and 30 second mark of this video, shows how to remove the valve. That blue propane bottle is the one you want. The valve is a Schrader type valve like in your inner tube valve stem. Get the tank clean, then drill out the big valve with a 3/8 bit. Find a connector hose, drill out the inside crap so the gas ca flow from the tank to the carb. That first Schrader valve you removed? Use that as for attaching a vent pipe. I would silver solder a tube to it so that it could be oriented so that teh vent tube does not leak fuel. You need to add a fuel fill hole and cap. There are suppliers of fuel fillers or you could jury rig one out of something. If you orient the tank the right way, the vent can be on the filler cap, then you can plug the Schrader valve hole.
2 propane bottles can have the tops off cut and attached top to top, to make a longer one, then add the filler and a standard fuel pitcock. You need a welder for these. Just make sure they are empty and cleaned out before cutting and welding, are we will meet you after we are dead to tell you what you did wrong.