My 70 was mostly painted by spray gun (CCSpec sourced paint exclusively). Besides why not support one of our sponsors. The frame and axles done professionally. The tower, hood, grill, etc. by myself and actually my first spray project. I was satisfied with my first spray job. Spray gun from Eastwood, Pottstown, PA, model 100HVLP. Good prep on all surfaces. Like was said good prep is one of the keys.
Rattle can is ,I think, best choice unless you are going for museum quality. Tractor is going to work and is going to look just as good several weeks down the road no matter what you use.
Charlie has the best--spray can or bulk