Interest in a PDP-8/e/a/f/m 32K RAM kit?

I'd check the parts list as well. If something is shown as "7430" on the schematic, but "DEC7430" on the parts list, that indicates that it's a part that was screened to DEC requirements beyond the normal specifications, usually under contract by the manufacturer. My main issue with your analysis was the assumption that the threshold of the input could be assumed to be halfway between the Vil and Vih specification. I agree that meeting driver specs is much easier than meeting receiver specs. For Unibus and Qbus, both drivers and receivers have an additional spec for maximum loading with Vcc not applied, and many of the older logic families don't meet that. However, there isn't such a spec for Omnibus, presumably since the bus expansion is more constrained, and the system isn't expected to work unless all the Omnibus boxes are powered.