I went on rock auto to see if any of the new senders specified the “on” pressure. The AC Delco one says 4 psi.
https://www.rockauto.com/en/catalog/chevrolet,1984,k30+pickup,6.2l+379cid+v8+diesel,1053021,electrical-switch+&+relay,oil+pressure+sender+/+switch,4588