I used MJK's Mathcad worksheets. Check it out at Quarter Wavelength Loudspeaker Design. The problem is still line length, tho you can probably model a much more tapered line.
It didn't last long. Just an experiment. Sounded fine, but not enough for the huge size. I went low Q sealed, as I never cared for ported designs. My current is a 16 ft^3 sealed dual Tempest, eventually being replaced with a quad AV12 sealed unit, if I ever get off my lazy butt and build the ent ctr it's going to be housed in.