It's quite likely that you could use something like a UC100 motion controller with very little work. It's not a USB-parallel converter although it looks as if it is. Install the plug-in to Mach3, configure ports and pins, and you are more-or-less there with no rewiring. Better performance than native parallel port, and you can use it with 64-bit Windows versions (which don't support parallel port, as you probably know).