Different stuff does different things together. In my experience touching up an old paint job things are less likely to react.
Fresh paint does different things, a new coat/two tone on something that hasn't cured for a long time can react, curdle or shrink the paint underneath. Even paints that are made to use together can react if both coats are fresh.
The fancy blue 3m striping tape especially made for the purpose if bodywork and can wreak havoc by pulling off a coat after you paint your line. I don't recommend it on uncured paint at all.
Lacquer on Lacquer with a rattle can be easy, I've touched up furniture and guitars with a rattle can. Best to be as dust free as possible, low humidity. You can build it up into the old laquer on a chip by just pointing the can and one quick spray. Smooth it out with thousand grit paper and finer depending the finish you want, repeat as necessary.
It might work, but I would test an area or other part if I could, and as far as decals, I think laquer was always the way they were done in the day, right? You may not want to do the whole tank and obviously keep the gas off them.
