I vote repaint. That's not patina, it is rust, and it will continue to grow unless it is stopped. If it was a vintage guitar, or antique furniture, or piece of art, I would say keep it as original as possible. I think a better analogy is an antique wooden boat. Would you keep the leaking caulk and missing varnish, because it's original? Of course not. It would be fixed.

I understand the value and sentiment of original paint, but I don't feel that allowing the object to decay is worth that value.

If it is repainted, it must be done well. A bad repaint and bad decals will kill it. The bike should be photographed and the decals carefully measured (like +/- .010") beforehand, if it is refinished.

At a minimum, the bike should be bathed in evaporust and waxed. Insides should also be treated with framesaver or something.