Well I'm just gonna state the numbers.
The 920 closed chamber 66-67 measured up 66.5 and were touched once by a shop..so I'd bet money they a are really 67 cc's.
The bone stock 675's from 1971 in the thread 318 average joe bla bla measured 68cc. The later 163/563 are 72cc the 315 were 66cc.
They used to say the heart shape 64 273 heads were 64cc. Anyone have some to know and share, please. I heard they were cracking sobs too. Idk. The 302 is an actual, amazingly, 64 cc's. If they had cleaned up the chamber some around the valves they would be the same 66-67cc the rest of the closed chambers are.
Now 302 are 64 CC, look at the chamber closely, the widow's peak between the valves..the encroachment of the chamber...
Now the 273 920 head... no encroachment of chamber, no widows peak between valves... got it?
Now tell me that the 920 isnt 66-67cc stock. 3 cc's is all it is.. but I know some cant wrap their head around that.