Here is the short version of a long story. I opened a box in my shop that has been there for 36 years.
Inside is a NOS Norton 750 head complete with original invoice from Norton Villiers to Suzuki of Oregon City (my folks, Suzuki, Kawasaki and Norton dealers in the 1960ís and 1970ís). The invoice is for part number 060988, cylinder head, $160.00 dated 1/12/1972. Thatís the correct part number and price for a stock head (I still have the parts and price books).
Here comes the twist. The original packaging inside is labeled Plumstead cylinder head, no. 8, F/S 180.
If I remember correctly this was a combat head that Norton provided to those of us on the AMA circuit. There is no casting/part number on the head, you can faintly see the BYRCO logo.
It looks almost identical to a stock head except the relief for the push rods is machined away from the valve instead of towards it.
Any help in identification from you Norton experts would be appreciated.