To paint lug line trim, use a Sharpie paint pen, it is *lots* easier than using a brush.
This Legnano pin striping was done with a paint pen by an old man with poor eyesight and shaky hands...
I would stay away from model paints. I am not sure how they react to sun light. I use
RustOleum or something just like it. Cheap, readily available and easy to use.