I kept the Servo Dynamics drives and SEM servos, but I have replaced all of the encoders. Right now, I have the machine about 80% done. The spindle control works fine, I have axis movement under Galil control, and all of the additional functions (coolant, tool release, master control relay, etc) are under control of the Galil + PLC.
There is quite a bit left to do. I have written the new PLC code for the tool changer but not tested it. I bought a touchscreen panel that is working, but needs to be mounted and I also have a pendant to integrate. I am also in the process of mounting limit switches for X & Y for safety and to reference the machine (limit + encoder index homing). Will try to get a picture of the photo transistor boards today. As I recall, it is just 2 pc boards mounted in a housing. Like I said, very simple circuit, but it will be some work to make.
I do have the PLC logic off of mine. Yours is probably very close if not identical. The main reason I changed the PLC is that it would take major programming changes to interface with the Galil as opposed to the Dynapath. I decided that my time was better spent on a more modern, more servicable PLC. The new PLC is a Siemens S7 series, cheap hardware and software off of ebay. The Galil communicates things like spindle direction, coolant requests, and tool numbers to the plc which then drives relays to actually control the machine.