That's a mouth full, but honestly, that sounds like a setup where you're asking for issues.

First off, Aeroquip sells the proper fitting for our cars, where that factory oil perssure sender goes, as it is not actually 1/8" pipe, it's very close, but in fact it's an English pipe fitting. If you're hard up, and dont wanna spend the didge, you can use 1/8" pipe, and just tighten it down, it shouldn't do any permanent damage.

You should NOT use COPPER fittings, they are very prone to crack, you should use aluminum, which will also not corode, and depending on whether it's mechanical or electrical, you should run a short stainless steel braided hose from the fitting you put in the block, and then run a T or Y, or what ever you feel like using. At that point, you will have an outlet for an oil line to go to a gauge, or to a sender, which by the way, the autometer senders are not all that reliable, and the couple I've used have leaked under really high pressure. Mechanical is much more reliable as far as accuracy, and as far as an oil leak, as long as you use stainless braided lines, and alluminum fittings you're kool. I've had an oil pressure gauge on my car for well over a year, without incident, knock on wood, and it's mechanical.

As far as the O2 sensor wire, if you're hooking up one of those flashing air/fuel monitors, they're very very unaccurate, and give you a false sense of security, and on top of that, they can frequently cause feedback and ruin your O2 sensors. If you're insistant, call any shop that sells and installs them, and they can tell you.

Good Luck, later,
Aj