I have installed the NEMA 2000 network wiring on my Grand Banks. I currently have a Garmin 5212, and Garmin 24 HD radar tied into the NEMA 2000. I have just added a Maretron tri-ducer, which will send speed, temp, and depth to the NEMA 2000 network. The beauty of the NEMA 2000 system is that you can build on it and add components as you wish. Maretron does not have, at this time, a device to convert the engine analog signals to the NEMA 2000 system. Garmin does not have such a device either. The Maretron device mentioned above is for engines equipped with a plug in wiring harness, which I believe would be much newer than your engines. I have 1990 model CAT's, and the Noland RS 11 is the only thing that I have been able to find (per the techies) to convert engine analog signals to NEMA 2000 protocol. I have not yet purchased that module, and have moved it to a lower point on my wish list, choosing instead to next install the Maretron systems to monitor raw water flow to both engines/genset, etc. Maretron has been very helpful in my questions to them.
Hope that helps a little.