273 Build

The only explanation i can offer you is the 920 has had a valve job, seats/faces ground while the 675 had only a bead blasted factory valve job...and thats the diff.
With the exception of .400 lift, the numbers are very close everywhere else. If i were to find that same cfm difference from .100-.300..then id have to say there is an advantage using this casting...but its like the 270cfm @.500 lift head vs the 300 cfm @.700 'with only [email protected]' and the cam used is .520
I like the 920, id use it, and its 2+ cc smaller chamber 66cc than a 675 is @68cc. Do i have a preference? Well... For what i would do with them, not really.