Tractors in the 1950s were not normally photographed in accurate color, perhaps due to the cost of home color film, perhaps because of mediocre processing results. This makes it incredibly difficult to discern what the correct tint for these antiques are. If you are lucky enough to find a tractor that has been shed kept for many years, the color may not have faded much. A paint shop can get the original mix from samples or chips of paint scratched off the parts you want to restore if they have a color matching machine, and the color is not too faded. This is the only way to assure that the color is the exact same as the color still on the tractor. Otherwise, you will have to deal with finding a new shade that is as close as possible to the original.
Your choice of reds will depend on how red you want your tractor. Originally the tractor's red was very red. In fact, it was nearly blood red. However, many tractors still in existence today are either rusted out or a very pale orange due to the paint fading or wearing away. DuPont Centari C8508 is a paint that was widely used by General Motors during the mid-1980s on their vehicles. This red is very close to the original red tone. Finding this paint can be difficult. For those on a budget or unable to find DuPont paint, RustOleum Sunrise Red or Number 7762 is a close match.
The correct shade of gray is controversial and guesses range from RustOleum products to PPG DAR 31657 paint, which can be purchased on special order from automotive paint stores. PPG DAR 31657 is listed in the 1960 copy of Ditzler books on Ford tractor repair as the gray tone on the 1950s-style Ford 8N tractor. If you cannot access PPG DAR 31657, RustOleum's Smoke Gray or number 7786 is a nearly perfect copy of this special-order gray paint.
Steering wheels and the accessory panel were done in black; glossy for the steering wheel and matte for the accessory panel. Any black paint made for repainting steering wheels or accessory panel plastic will work for these.