Port size question


I'm working on a pi-aligned box for some 12" Daytons and Pi-Align gives me a port size of 4.68" x 11" long. Is there a way to resize that to a standard 3" or 3.5" ID? I don't have room on the baffle for a rectangular port of 1/2" or 3/4" material.
Thanks very much in advance.
John


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