Hi,
Well, my painting method is rather poor by comparison to most folks. I put the thing together less the tin bits, wire brush what's there (old paint and rust), then put on two coats of new paint - with a brush. I don't even bother with primer, as machine enamel tends to do well as it's own primer in my experience.
The only bits that get sanded and spray painted are the tin parts, and that's because they're actually smooth and would show brush marks.
My thinking is that these are tractors and the paint exists to keep them from rusting away too quickly.
Then, too, I don't make up show stuff. Oh, it might go to a show now and again, but I have this tendency to keep right on using my old iron to do work. Perish the thought!
As I fix the leaking cooling system in my 420c, I'm going to get loose with the can of paint and brush. My intention is to paint where there is no longer paint, but I'll probably wind up painting most of it in the end.
Stan