I have replaced my Neco with a Simrad AP22, I kept the series/shunt motor which is a very powerful unit, found a supplier for new relays, and adapted it to work with the simrad digital signals.
All this was done with the help of an Italian teacher from the University of Rome who is an expert on Neco and has assisted others to convert.
I will check, but I think there is a document on here detailing the work needed to be done, if not please feel free to email me directly.
Best wishes
Mike