You've suggested a port of 2.75" diam x 2.75" long to tune a 2.0 cuft to 40 Hz (with a Qe = 1.3)

The port sizes I have available are 2.67" diam and 3" diam. In a 2 cuft cabinet the 2.67" diam port needs to be 2.625" long to tune to 39 Hz with a Qe of 1.2 . The 3" diam port needs to be 3" long to tune to 41 Hz with a Qe of 1.3 .

Which would you suggest and why?

And one last thing, looking at the document that comes with Pi Align you suggest that for bass reflex enclosures the port should be a
woofers' diameter away from the center of the woofer. Is this critical? Why? The port is also located in the corner of the cabinet. Is this critical? Why?

Thanks again for the help,
Jeff