Hurco BMC40 retrofit

I'm retrofitting a Hurco BMC40 as its 486pc based control based on crazy proprietary boards & OS finally died.

I'd appreciate any advice related to hardware for the retrofit. 

From my initial research it looks like this has analog drives. (Yaskawa cacr-srca 20bbb? Pic attached)
The spindle drive is a Yaskawa CIMR-MTIII-11K. 

If anybody is familiar with these drives I'd love to verify that part number and if its analog +-10 or step/dir. I *think* I found the manual for it but not 100% sure. 

Initially I'll just be getting it back up and running with basic 3 axis + tool changer but I do plan on adding a A & C axis trunnion table and seeing if I can get it rigid tapping. 

I'm thinking a 
Raspberry Pi 4 + 7I92M + 7I77

I think that ethernet setup will be nice as the user control panel is pretty far away from the motion control cabinet in the back of the machine. I can have the Pi in the display / interface end for the operator, put the mesa stuff in the control cabinet and then its just a matter of power and ethernet to connect it up. Although there will probably be stuff like the MPG etc that will need to be wired back into the cabinet in the back with the mesa stuff. 

Would it make sense to also get a 7C81 RPI FPGA board to put in the user control panel to run MPGs and buttons, feed knobs etc? Does that work? Using a SPI device as well as a ethernet? Can Linux cnc handle that? Am I over complicating things?  

As far as user interface hardware, any recommendations of things to look at? Screen, enclosure, MPGs etc? Anything pre-fab or should I make my own cabinet? 

I think that's all for now. I'll be keeping this thread as a build log so if your from the future scroll down  

Ah thanks for that. I searched the forum but only saw posts saying you did a bmc20 a while back but never could find the actual thread. Didn't think to do a google site search.

On the RPI I have seen this recommendation elsewhere but I don't know what it is that people don't like? Are there latency issues?