The gauges you are currently running are hooked together via wiring;
Oil pressure swith will ground and light on dash to show no oil pressure - located front of block 1.5 prob same on 1.6/4g63
Mechanical oil gauge will need a capillary tube installed into the cab from a tee on the block where the pressure switch currently sits. This will get you pressure reading.
Coolant temp will come from a copper tube with spiral metal wrap cover from a location on the side of the thermostat housing (if similar as 1.5 location) you need to find the connector for the dash signal versus the one sent to the computer (you MUST leave that one connected)
Tachometer pickup is electrical as are all the other tach setups, just different inputs. Needs a special hookup on the wiring if you have coil packs but I don't know for sure.
Volt/Ammeter gauge will need an electrial hookup. Volts needs any wire but can't figure (too tired but voltage will be better if taken near the alternator because it better isolates problems (like your gauge wiring lighting up in your dash from a light socket you might have left exposed and hit metal ground while live! oops....) Ammeter uses a setup attached near/at your coil.
All the gauges may need a path to power and/or ground for backlighting
You may have to drill a hole(s) and use grommets to bring the tubing/wiring into the cabin. Haven't looked at that on much yet as far as pulling wires into the cab. Others may know more there.
That's all I can think whilst I sit at the 'puter with my eyes half way to my eyelids halfway to my knees.
Anyone else got something for our guy here?
Tim will sleep now ..... zzzzz
(hope this solves any problems)