Yeah have tried that on a spare tank before (compressed air), never again haha, was waiting for it to rupture but ended up causing a heap of pinhole leaks.
Damn, have stopped by one panelbeater who said to give the PDR guys a shot first. Lighting makes it look stoved in pretty bad there, might as well get a new tank at that point.
Will try that cheers!
Bike is 38 years old, I have no idea exactly how old the paint is though, definitely a respray in the last decade unless it was kept in a cave.