Sorry haven't taken many interior shots of 67 C code air cleaners Here is one and you can make out the black in the lower sections. The lip where the air cleaner sits on the carb may originally not been painted. This may be how it was held while the paint was being applied but can't be sure. You can find that detail on some of the NOS & service replacements. Can't be seen on an assembled car. Picture below is of a Thermactor style one but 97% of the details are the same
Over all shot of the exterior of a 67 A code air cleaner for some additional details
......................... The air duct and heat riser are painted Ford Blue separately - I think. Some ducts and wing screws were painted assembled.
Yes all three (base, lid and snorkel) were painted separately. Never seen one with a paint shadow on the base from the "duct" and wind nuts being installed before painting.
Would suggest going with the unpainted wind bolts