Hi Bwhite,
At $20 a foot plus termination, I could make you up a set of DH Labs Q-10 for triwiring. I'd like to know the driver configuration and which driver each post set is connected to, but assuming it's a 3 way crossover, you can go with one Q-10 configured internally as a 10 gauge cable to go to your bass driver(s), then have the other Q-10 in an internally biwired configuration of 12 and 14 gauge. It should provide a nice overall current-carrying balance and great sound at a good price. The two cables can be spiraled up together for a neat appearance.
I agree with the posts above that you should not mix different brands or designs that are not especially made to go together. Their different electrical and sonic characteristics can play havoc at the crossover frequencies, a place especially where you need a good, smooth blending.
Jeff