yeah, when i first got into vintage moto stuff it was 2004 right after ethanol gas came out, kreem version 1.0 was not ethanol safe because the people that originally came up with it never anticipated anyone doing something so stupid as putting ethanol in gas.
well, for a few years there, motorcycle tanks that had been 'kreemed' 10,20 years ago were all turning into snot, people would go out to the garage to get their bike ready for summer and the carb would be disintegrating and the tank would be full of the nastiest shit you've ever seen, and i would buy CB350's, CB750's, etc. all day long for 100 or 200 bucks, you couldn't give the things away. my buddy was a tow truck driver and he was picking them up 3 or 4 at a time. If i had a dollar for every $400 mint condition RD350 or CB750 i passed up back then, i could almost afford one now.
so... ever since then i've just got a real bad taste in my mouth for any of the 'goop' type sealers.
I do most of my refinishing with catalyzed urethane single stage auto paint, its relatively cheap, it sprays on super nice, and its fuel resistant, basically fuel proof. You do need a good air compressor with filter, drier, and a HVLP type spray gun.
My buddy maize builds some of the nicest bikes around, he does a base coat using high end rattle can, then clears over it with spraymax 2k clear (which is a rattle-can catalyzed urethane clear) the finish is top notch pro auto body grade and it can all be done by an average guy in a garage with no tools.
Powder coat doesn't melt from gas exposure but it can get chalky or change the finish if its a matte finish. Personally, i don't like powdercoat because you have to strip down to bare metal and you cant bondo, but it is tough as nails. Its great for stuff where you just want it to look 'pretty good' and not get scratched... like mopeds... but its more cost/work and its something that you gotta send out