Raoul,
Sounds like you have the restoration well in hand. Regarding the "pipes" you mention, the temp gauge uses a liquid filled tube that is factory sealed so no chance of blowing anything through there. The oil pressure gauge has a line leading into the gauge that terminates in a brass bellows that is pressure affected to move the needle on the gauge. If you put air to it, the gauge should move, but too much air pressure will damage the unit..easily. If your truck runs, the best thing to do would be hook the gauges up and see what they do. If you are in doubt, you can check their accuracy with a thermometer in the radiator fill or another mechanical oil pressure gauge 'Teed' into the engine. Even a pot of water on the stove with a thermometer can check your temp gauge.
I wouldn't move the needles by hand too much..you might get a surprise. Good luck with your restoration.
Stuart
