Sounds like you and I are doing similar things lately.
Been fashioning up harnesses to test opto boards on my WPC and WPC-95 fixtures as of recent.
Amazing that I've been looking for fixtures for years, and in a period of 90 days, the WPC, WPC-95, and Sys9/11 factory test rigs have pretty much fallen in my laps, all at pretty fair prices!
you must have a big lap, John ! I'd love to have just one of those fixtures.