Use design software to select subwoofer driver for existing bandpass enclosure?

[rickhoutx]

This is for home audio use, but I thought the experts here might be of help. I have a bandpass designed Paradigm PS-1200a subwoofer and as a thought exercise I would like to use two or more software packages to see what 12" drivers might work well with this beast of an enclosure.  Unless I am missing something trying to use WinISD, the program wants me to start a project with a known driver and ends with an enclosure recommendation. I am trying to do the reverse.  Can anyone recommend a software package (free is always best) that will do this?

 

Thanks - Rick