Let me tell you my experience with gauges.
I too was like you once, and had gotten tired of looking at the piece of crap factory gauges that really only tell me how fast a needle can move back and forth. So I bought some Autometer gauges. Sport-comp water temperature and oil pressure, both electric. The water temperature was a breeze to install. I went to the local parts store (Advanced Auto Parts, or O'Reilly's or whatever you have) and bought a new waterneck with a hole drilled for the sending unit. All aftermarket waternecks should come with this. The oil pressure gauge however has been the bain of my existence for too long.
To hook the sending unit for the oil pressure gauge up, you'll need to remove the stock sending unit from the block, it is located in front of the oil filter. If you want to run both gauges, the easiest way to do it, is to buy an 8" 3AN steel braided line from summit or somewhere. These are commonly used as nitrous lines. Get one 3AN to 1/8" npt all male adapter, and one #AN to 1/4" all male adapter from summit, an 1/8" all female tee-fitting (parts store), and a 1/4" female to 1/8" male reducer (parts store). Run the nitrous line from the block (3AN to 1/4" fitting), into the tee-fitting (3AN to 1/8" fitting), using the adapters from summit. On one end of the tee, put the factory sending unit (might have to buy a new one, as the factory one usually breaks when you're taking it off), anyway, put the factory unit on the tee using the 1/4" to 1/8" reducer. On the other end, put the AM sending unit into the tee, and then all that's left is the wiring. Make sure to attach a ground wire to the autometer sending unit as it might not work without it. Be sure to get all your lines and fittings real tight, otherwise they are going to leak bad. I used teflon tape, and that s h i t doesn't work at all. I'm gonna redo it all with RTV or something that I know will seal it up. Good luck, let us know if you need anymore info. You can PM me if you want, I have been messing with my gauges for 3 weeks now, and they are FINALLY WORKING!! lol