If its a true 67 head then it would be a closed chamber with 2.08 and 1.74 valves. And if someone had changed them they could be newer but if it hasn't been apart my bet would be 72 cc's and 915 heads. The heads that came out the years before were called 300J heads and they look just like the 67 440 HP head but have a smaller exhaust valve and a much smaller intake port, and they don't flow anywhere close either. The 67 HP head has a 906 intake port as this was the first design for the 906 and the last of the HP heads and the closed chamber. Then the factory made a open chamber head for emission's purposes, this chamber was changed to the 906 and later open chamber design. The intake port wasn't changed until 72 and stayed this way until the Big Blocks were discontinued in August of 78. Also in 72 they flame hardened the exhaust seats for unleaded fuel's, as the eariler heads have to have the hard seats installed.
