The colour of Chevrolet engines has been hotly debated on Chevrolet forums for some time now, and I confess that I can never remember. However I looked up a forum I replied to and it may help. Yes, that's me..'Oracle', a Moderator and have been since 1999.
Try this link
All the photos I have seen of new chassis, factory-fresh, seem to indicate that they were painted the bluey-grey. However a photo inside Walkerville/Windsor Transmission Plant taken during the war showing hundreds of 216 engines suggests a darker colour.