To switch to UCCNC, I'd recommend a UC400ETH. You just need to get a cable to plug the breakout board into the UC400ETH. You'll also need a UCCNC license, and a small power supply to power the UC400ETH.
This assumes everything was working with Mach3 and a parallel port into that breakout board.
A UC100 is a little simpler, but the UC400ETH is a better choice imo.