The electronics package now works correctly. The inputs didn't work yet, but I found out that the latch signal was active low. I changed the programming again, and that now works too. The outputs still work with the altered programming, because the output latches are edge triggered.
As you may or may not be able to see in the picture above, The electronics are mounted in two layers of pcb's on an aluminium panel that fits behind the blank panel of the IBM console. The pcb's with the connectors are mounted on a second aluminium panel. I now need to sandwich the two aluminium panels together. To this end, I need some long helical ridges wrapped around steel cylinders, which necessitates making a trip to the hardware store to get some (bolts, that is).