A Dodge 270 is not a Chrysler 331.

Other than some nuts and bolts and the term Hemi they have nothing in common.

They are not in the same family at all.

He's taking the 331 out .065" over, which always ups the compression ratio some. 677.93 cc for stock bore 331 vs 722.67 cc for stock bore 354 (0.65 over)

The 331 heads he has CC at 102, 354 heads (which these are not) average 108 cc's. That will up the compression as well.

So you have almost 45 cc more bore volume going into 6cc less chamber volume.

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.