"If I'm not mistaken, using sending units would require the services of the computer."
A '94 Chevy truck would have an oil pressure sender and 2 temp sensors, the oil sender operates the gauge directly, as does one of the temp sensors (the one in the LH head), (the temp sensor near the t-stat keeps the 'puter informed of coolant temp).
Simply adapt the old oil pressure sensor and correct engine coolant sensor to the Cummins, (using reducer bushings, if needed), and hook them up to the main wiring harness, the gauges won't ever know there's a Cummins under the hood, and will work as before.
Having seen a couple of engines ruined by a melted or worn-though plastic oil gauge line, or a worn-through or cracked/broken steel or copper line, I'd stick with the electric gauges.
Yep, the drivers/operators should have noticed the loss of oil pressure (and oil) in time, but it doesn't always work that way in the real world!