Well, to model the response of the WO(not exact but a rough estimate) plug in your drivers into a 4th order BP tuned to 45hz with the same size chambers as the WO you are building.  You'll have to decide what version you are building and then calculate the volumes.

To optimize the WO- try to find the best 4th order setup tuned to 45hz still.  You'll want to keep the compression (ported chamber) volume the same as the WO plan.  But the sealed chamber can be made larger by adding to the sides, top, whatever.  Or smaller by adding solid materials to take up space.

All in All though- I built all of my WOs without any modeling or modifying (Well my first 12inch version was scaled)  and all turned out awesome.