Quench, I would say that the 670 heads would have far more of that vs the open chamber 6X heads.
Flow, the 670 heads for several years (with a good valve job) were assumed to be better flowing vs the #16 casting 1968 GTO heads, the "later" Emissions heads, and the non early SD 389/421 heads. Only the 455 SD heads and the RA-IV heads were better.
As posted before, easy to get a piston made that would have a 9.1 to 9.5 compression ratio with the 428 cid engine.
Tom V.
The emissions heads are good for emissions. But do what you want.
10 or 15 cfm difference in port flow is not going to do much on a street engine.
Now a Boosting device!!!!!!!!!!!!!!!!!!!!!!!!!!!
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"Engineers do stuff for reasons" Tom Vaught
Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward.
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