Question:

Can you use an automotive paint on a glassed warbird followed by a coat of clear coat?

Yes. Just don't over-do the primer. Use the primer carefully, and sand it almost all the way off. That fills only the lowest spots. Repeat another time or two until you have only the low spots filled and the entire surface of the wood leveled. Then spray on a very thin coat of primer and afterward, the paint. That will give you an excellent finish. Depending upon the paint you use, you won't need a clearcoat.

You do need to be very careful, though, with the paint. Some paints are toxic even with a good mask for organic vapors. Some automotive paints will require that you use a positive-pressure air-fed mask to make sure you get clean air. The intake for such a mask needs to be well away from the paint vapors.