So, if you were to put a slot port that is 7.25″ x 0.33″ x 14.67″, that is equal to a 1.75″ port. Slightly larger than the 1.5″ port that Paul Carmody uses in his build. That would give a bit more wiggle room to help reduce chuffing at the expense of a longer port. And it would still be optimally tuned to 35.7 Hz F3.
No, I didn’t use WinISD, so I don’t have any other numbers. But this should give you a starting point to work with.