Standard flare fittings for gas use are typically JIC - 37 degree, or SAE - 45 degree. I'm not sure if what you have is a proprietary fitting, or a pipe vs. tubing issue. Most of the Big Square Box home improvement stores carry limited inventroy when it come to plumbing fittings. Have you tried a plumbing supply house, or maybe even McMaster-Carr?
If your not sure about what you see in their on-line catalog you can call their customer service line. They have been very helpful to us. I recently had to order some 4,000 psi JIC fitted hoses for a project, and they walked me right through the inventory with hoses, fittings, adapters, etc...
Does this look like what you need?