THNDER,
I've been out of town for several days.
The casting dates on both heads is C 6 70 (March 6th 1970)
As far as the NOS Air cleaner, It is still in the unopened box and I really don't want to open it right now. I have had several generous offers for it and I'll probably sell it to help pay for part of the restoration. I'll ask whoever I sell it to if I can open it.