I am working with Darin Molnar of Tortuga Early Instruments to convert a Rodgers 32B console for a VPO. We are using a Teensy 3.6 for the three manuals, pedals, pistons, and stops. The stops are not SAMs but the encoder could certainly handle that task as I've already used the same setup to add a capture system to a Moller Artiste.
The sketch for the Teensy will be published once we have finished in a week or so. The input boards shown are totally vanilla shift registers using the 74HC165s. That makes the Teensy setup compatible with many existing consoles including those modified with MIDIbox DINs and DOUTs.
As always the PCBs can be ordered from https://oshpark.com/profiles/jkinkennon.
http://www.kinkennon.com/images/TeensyEncoder.jpg