I wonder how much of the dashboard could really be relocated. Bosch had just began developing the CAN protocol that year and chips wouldn't be available until four years later. There's an illustration I found [0] that shows how the modules connect and based on the history of the automotive databus, I don't think it would have been able to give you a dashboard as populated as the image in your link. There would need to be a pair of power pins along with a pair of pins for every value you would want to read out (either for analog voltages or RS-422 since SPI/I2C/CAN had not been invented yet). I'm guessing there might have been hard restrictions on some modules like the stereo and speakers, why would you want the speakers to be anywhere else in the car? Going off of the typical dashboard in the 80s, you have speed, tach, fuel, battery level, oil temp, radiator temp, and the odometer and a trip meter. Maybe integrate the trip meter with the odometer value to reduce the 3-4 wires needed for displaying/resetting it. The clock would only need power. Then add in the climate control, that has to be at least a couple more signals for temperature and fan speed and maybe an on/off for the AC if it was available at the time. Don't forget all the status lights, that is going to add a lot more pins to these connectors. The actual pictures don't show any of how they connect. The illustration shows what looks like two connectors. Maybe that's how they did it, two 25 pin d-subs would probably be enough for running everything out to every module dock, impractical but possible. You could accomplish this today with a single 4 pin connector: power, ground, can+, can-.
[0] https://cardesignnews.com/media/imported/servlet/file/275197...