Grant Erwin wrote:
...
I cannot imagine any paint that can stand up to HCl, either. ...

I routinely de-rust with muriatic/HCl. There is often some paint on the
rusty piece and I've not noticed that the acid has affected it. If
there has been an effect, it was very minor. But I still suggest a trial.

... Even if the paint could stand up to muriatic, I very
much doubt the decals would.

Well, the acid can be very aggressive with some materials, but totally
benign with others. It really does depend. I would not be at all
surprised if it did not affect the paint or the decals. But I can't say
for sure.

Bob