A picture is worth a thousand words IRL for most folks, but in your case that increases by an order of magnitude. Is that Hardi Panel sheet covering that booth?
I come from the world of late 80s - early 2,000s use of dongled software and proprietary interface cards for CAD-CAM in signmaking. I'm more interested in the fact that you're still buying production equipment for that production environment! I take it your production software was never made PowerPC compatible? If it had been, I'd suggest looking first gen NuBus PPC machines for future use. Rock on!
edit: second thought, BMOW has developed the
USB Wombat for converting modern KBDs to ADB for your Macs. Buy a few of those and replace the ADB KBDs with current boards hardened for industrial use or far less expensive consumer KBDs for which you can stockpile clear vinyl(?) KBD protectors to seal out the oil, grime and dust.