S.H.A.F.T.
You paint the grill what ever color you want, after all it is your tractor.
The grill on a 127 was originally cadmium plated when IH built it, but there is no way of knowing what previous owners may have done to them. Some people paint them black because it does not show the dirt from the engine and it blends with the black headlight panel. The heat from the cross mounted muffler would also help cause the grill to rust over time, and they would get painted or coated because of that.
Some of the sales brochures (which are not always the best source of reference material) make the plated grill's appear to be white in color, but the only grills that were painted white originally, are the ones on the Original model built from 1961-63, and the 70 & 100 built from 1963-65. All the others were plated until the wide frame models with the black, waffle pattern, plastic grills (models 86,1X8/1X9 built from 9/71 till 10/74), and the black painted expanded metal grill and black perforated metal headlight panel of the Quietline models (800-1650, built 10/74 till 6/80). The "red" 82 series (built from 7/80 till 4/81 by IH, and untill 1985 by CCC) had a silver painted grill with a black screen behind the grill, and black perforated metal panel for a headlight panel.