CHEVROLET ORANGE if it's a BB. I have them ceramic coated grey, then CI grey paint, then Chev orange. When the orange burns off the lower portions you have a near perfect orig look. See attached LS6 photo and Z16 photo down the page here:
http://www.z16chevelle.com/restoration%20photos.htm
Exhaust manifolds were installed BEFORE engine paint on big blocks. This is proven by several low mile orig paint engines (cars) I've owned and numerous I've seen as well as several color factory photos. Also shows in 60s assy line photos and assy sequence descriptions. Sorry grey guys......
Dave