I'm sure this has been done before. With so many old lamps waiting for pump cups from overseas, I use this gadget to make sure the lantern is ready for completion. It's simply a bicycle tube valve, a French valve, secured with its nut, and a rubber seal (flat washer) behind. A few pumps with any bike pump are sufficient. A Schraeder valve - no, too much pressure is lost when unscrewing the connector hose, and someone might put a compressor hose on it. The earlier Woods valve would be best, as it has a piece of rubber tube which is easily replaced. A bit hard to grip this one, I should have made the two ears larger. Suits the Companion, Primus and others. Now looking for a spare Coleman filler cap, for the next mod.
Well fettled! I also liked the old Woods valves on bike tubes, if the valve failed the whole tube did not have to be changed, the link below shows images of those valves. woods valve - Google Search