I just finished rebuilding mine. I used gloss caliper paint. I'll post up a pic tomorrow. came out very nice.
I lightly honed the bore first.
Degreased and cleaned it several times to make sure I avoided fish eyes,
Plugged and masked all the holes plus the cap threads.
Finally degreased and cleaned it several times to make sure I avoided fish eyes, Sprayed and let it dry a couple days. I gave it plenty of time to dry before I rebuilt it.
I don't know of any truly dot3/4 resistant paint. Caliper paint is usually for temp not fluid resistance. Powder coating may be another option, again prep work would be the same but even more important to mask areas when you don't want build up.
Works and looks nicely.