I'd forget about upgrading if cruise is important to you, it's not possible with the Pulmore motor. No Legacy option either, at least not at any price you'd want to pay.
The only way to get cruise is first upgrade to a can motor, Frank Timko does those conversions. Then you can upgrade the electronics using ERR parts for the electronics. This will not be cheap, and these will have anemic pulling power with the single small Mabuchi motor driving only one truck. I've done a number of these single motor diesels exactly that way, the only realistic way to run them was in an MU consist with at least two and preferably three powered units to get enough motors and wheels in the mix.
