This can be quite frustrating I know. Thanks to Chris for posting the sticky! 

If you are furnishing the paint, talk to your painter and see if he has a preference on brands. He will explain the quantities and qualities he prefers. You can buy $25 a gallon paint or $200 a gallon paint but he should let you know what works best for him and your budget. When you go to buy the paint take all the info off Chris's thread as you might need several cross reference examples. Also, if you have any part that has original paint on it, take it along with you to the paint store and compare what they mix up to the part you have. Color matching is also a possibility but sometimes difficult with 60 year old paint. 

Your 1950 77 has a darker tint than the models 1952 and thereafter so be carefull with the codes. 

I have been using DuPont Nason line with good results - I have a jobber nearby. Buddy uses PPG with good results. Lyle uses MS and likes it. Just find a paint brand/store that you and the painter are comfortable with. Good luck and let us know if you run into any problems.

THE YELLOW PAINT USED ON GRILLS =
Dupont 44087. Oliver Meadow Green for Fleetline series  For 1947-1951 = Dupont 1317
Red paint for all oliver wheels = Dupont B8590