What is the correct finish for a 71 b-body disc master cast or black? The booster is gold cad plated. Thanks, Joe.

Neither, Joe. They had a gray coating I'd describe as being like parkerized. Maybe gray phosphate. Whole master is coated, cap, body and bail wire.
Unless you're talking about a hemi car. 71 hemi disc is the same as 70 with the 2229191 casting number. And still all black like in 70.

Thanks, Brad.