I'm not planning on installing any gauges any time soon, but I've been researching this, and I haven't found much information. I've seen a few debates online about whether or not you should replace the stock oil pressure light with an aftermarket guage, because you have to unplug the stock sensor when you tap into the galley plug above the alternator. But why not do both? You can tap into one of the other two galley plugs for the gauge, or you can just use a sandwich adaptor plate. This way you'll have the comfort of knowing exactly when you lose pressure before it's too late with the gauge, and have the sensor light as a back up in case the gauge fails. Are there any downsides to having both?
This might already be answered somewhere, but I haven't seen anyone who talks about using both. And I know, I'm worrying about this too much for someone who's too broke to afford new gauges right now anyway.