If it is a problem with your fuel attacking the brass then what are you going to do about the brass tubes in the tank? I have always ran a heavy clunk that will follow the fuel in the tank and never had any funky growth in the tank.. Maybe I am just lucky.. I run two lines. A vent to the top and a clunk line. I put a large ID brass "T" in the fuel line in route to the carb and off the "T" run a fuel DOT or a line with a plug in it.. Fuel and defuel all through that line...

K.I.S.S.

Rick