Phil, Get a couple of blocks of wood to run the car up so the jack clears. Also with the gauge you have started at the wrong end of the diagnosis tree. Check the gauge end first. The power/light to the gauge are separate circuits so the gauges lighting up doesn't mean it's actually connected. Get a DMM and check the voltage at the gauge connector. You should be able to see voltage when you stall up the car in drive as it will make boost. Also swap the wiring between the oil pressure and boost gauge. If the boost gauge functions and the oil pressure doesn't you have a wiring/sender issue further down stream. You'll also need to check for voltage at the sender. Once side with have the signal voltage supply and the other will either have continuity to back to the gauge or to earth depending on how the gauge is wired up.