I had some rubber aircraft/military hoses custom made by Aircraft Spruce some years ago for my 1940 LaSalle. They will also make braided steel versions of the hose. Pilot Supplies, Avionics, and Homebuilt Aircraft Parts from Aircraft Spruce and Specialty Co. At the time (1987) a 5/6 inch line in rubber with AN fittings would cost you around $20/foot. More for braided steel. It's a lot for a hose, but considering what you're protecting, it's not that much.