I have found that the premium tractor colors from Tractor Supply work well. I use the Ford Blue and the International Harvester White and have been very pleased with the color match and the durability.
When looking for a match for my Beaver, I took the front part of the hood/fan shroud (the part with the little beaver decal) to an auto paint shop and they checked the color which I had buffed and polished and came up with a Nissan white that was very close to the original part.
I can check my records tomorrow and possibly find that color code and post it on here.
I believe I just used Ford tractor blue for the rest of the tractor.