RE: fuel proof spray paints?
I used to paint mufflers with one of the brands you mention back in the day. Used the high temp stuff.
I tried it last year and in spite of the muffler having about a week to cure which was way longer than the mufflers back in the day got, the paint went sticky and started to streak the airplane.
I assumed they changed the formula.
I bought and tried a box full of cans, every brand I could find. Every one got 3 or more days to cure and every one of them failed. Only the first couple got tested on an engine/plane. The rest just got some fuel spray. I've read since that some of the brands I tried worked for others. Got no idea why, none worked for me.