My a/c is LAA permit & I used acrylic 2pk at first for just such small touch up jobs. It all went solid after a few months of storage. I now have a tin of colour matched Polyurethane which I can thin with standard cellulose thinner.
The primer I use is Acid 8 etching primer, also thinned with cellulose. All available at automotive paint suppliers.
I have sprayed cellulose since I was 25, I'm now 72 with no ill effects & I smoke like a train, Still passing medicals.