Single stage or bc/cc for a vintage look?

If you are that concerned with original then use acrylic enamel. Why not take advantage of todays urethanes with their great shine and durability? If it were a concours restoration on a really valuable car I understand, but most of us just have run of the mill cars done our own way.

That's the problem. These cars (trucks) didn't shine like a modern B/C when new.

You want a factory appearance, go single stage and toss in some runs.