It may depend on the factory that made the truck.
I've looked at allot of pic's of 1950 trucks since that’s the year of my truck.
The pics of original un restored 1950 trucks seem to have both upper and lower latch assemblies unpainted metal, and hood springs unpainted metal. Radiator supports are black
On my truck I painted the latch assemblies black.
The two photos below Show a very nice, maybe over restored truck, but show the latch assemblies and springs.
reference photo reference photo 
