Help me identify this head please!



I have a 250 head of unknown year... the casting numbers are worn enough that I cant really tell what they are.

The head has a 1.75 intake valves, a large log w/ 1.75in carb opening. Near the carb mount on the vertical surface of the log is a flat spot that has two holes.. one threaded and one not, for emmissions I assume. I havent got a chance to CC the heads yet to find the chamber size.

Can anyone give me a estimate of the year? The plan is to finish cleaning up the head, milling if needed.. give it a light port and polish and replace the '66 head thats on my 200 right now.

Then I'm going to be creative with the '66 head :D
so it should have hardened exhaust valve seats already then correct?
I think I have a '77/'78 head too, (it will be put on this spring on my '65 Mustang 200) but how do you tell if it has a hardened (sp?) exhaust seat?Can you tell by looking at the metal? Should you be able to see a ring? The intake valve is 1.75 dia. Does that make it automatically a hardened exhaust seat?