Best fuel line thread sealant?

[HIGHWAY BY THE SEA]

I looked but could not find a thread on this topic. I replaced the old dilapidaded metal fuel supply line that runs into the filter of my GMC's Rochester 2 barrel carb with rubber fuel hose and used brass fittings to attach the ends to the fuel pump, and the carb. The brass fitting at the carb (fuel filter area) leaked even though I used some NAPA thread sealant on it. So I removed the fitting, put a larger amount on the threads, reattached it, and fired up the engine. At first it did not leak at all, but then a very slow drip began. I checked it, and it appears that the gas is turning the thread sealant to liquid. What should I be using instead for sealing this brass fitting thread? Silicone perhaps?