I feel like I am reaching back a thousand years or so... (Well it was another millenia ).
I used to use R&B back in the late 60's - early 70's.
Rather than rub and buff it, I used to thin it and brush it on. Got good results for the time. My "secret" was to paint in manageable sections and gently blow. It would "flash" over and even out nicely. Did a Monogram B-52 using that technique. I wish I could remember what I used as a thinner, but I doubt if it was anything overly exotic - pretty sure nothing more than a generic hardware store thinner. Might even have been turpentine. (Trying to shut my eyes here and remember the smell.)
The finish was reasonably durable and did take decals well.
Now, rather than blow, I'd suggest that if you find the right thinner it should airbrush nicely.
I'll have to see if I can dig around in some deep dark storage and find one that might have survived the ravages of the decades. It WAS a long time ago