heres a copy and paste of a PM i sent to someone looking for help, thats probably about all the info i've got, hopefully reading through that will help answer some questions, if you've got any questions about how i did stuff feel free to ask.
*note: i did my setup in a way which i could keep the stock dummy oil light on the dash. This makes it more difficult, but i felt like it would be a good thing to do. Also worth noting, this is for an electronic oil pressure gauge.... most people don't recommend having a mechanical oil pressure gauge inside the car, because that means oil @ operating temperature is being pumped to your passenger compartment, which can be dangerous.*
to start off with, the stock sender and the block are both threaded with BSPT (british standard pipe thread). However, pretty much no matter who makes your gauge, the aftermarket sender is going to be NPT (national pipe thread), and so will pretty much all the fittings you can find. This means that you have to do some special adapters and whatnot. For this, livelyjay's post at the top of the second page in
this thread is very helpful. The second list, under "1 aftermarket gauge with stock sender" Contains all the parts you'd need for your fittings, MINUS the pieces for the remote mounting (essential because not only is there not enough room, but also because you'd have a massive amount of stuff hanging off your block and vibrating and getting undue stress).
SO....
out of the block, you'll have the 1/8" BSPT male to 1/8" NPT female listed on livelyjay's list. From there, you'll go to a 1/8" NPT male to -4AN fitting (for your hose)(this is not on the list). You'll attach the hose here (i'll go into more detail about the hose later), and it will run to another -4AN fitting, but this time with a 1/8" NPT female on the other side. Next comes the Tee fitting thats on the list (The tee has i male and 2 female ends. the male side of the tee will attach to the female end of your hose fitting, leaving 2 open !1/8" NPT female parts). Into one of those, you will screw in the aftermarket sender. Into the other one, you will put the 1/8" NPT male to 1/8" BSPT male adapter, then the 1/8" BSPT female coupler, and finally put the stock sender into that. I know thats hard to visualize, and its a mouthful. If i need to clarify any of that let me know.
To mount this whole assembly some place, i hooked it to the underside of the intake manifold support bracket (you can't miss this piece, big black bracket thing right to the left of where your oil filter is.
Now, as for the hose.... i had ordered a stainless steel braided hose kit from summitracing.com along with hose ends, but it simply was not going to work, the hose ends were impossible to deal with, and the hose was really quite large around for the application, even though the inside diameter was just right. SO, i went to a local 'speed shop', and managed to get a hose that was also stainless steel braided, but i believe it was made of teflon so it was much thinner while being just as strong. I also was able to get one end of it with a 90 degree fitting which helped alot. I used the straight end coming out of the block, and brought it around to the left of the manifold bracket, using the 90 degree fitting to hook up to the tee.
The assembly with the senders, as i said, was attached to the mani support bracket. The way i orientated it, the male side of the tee was sticking out to the left, the aftermarket sender was sticking up, and the several adapters and stock sender were sticking out to the right. I put a metal hose clamp around the aftermarket sender and the bracket. I also drilled a hole in the bracket in the appropriate place and stuck a nut and bolt in there to allow the entire assembly to rest on the bolt, while being held securely by the hose clamp. In addition, to make sure the aftermarket sender was grounded very well, i took a wire that was bare on both ends, stuck one end under the hose clamp and the other in between the mani bracket and the intake mani where the bolts go, to make sure it made real good contact (if its not properly grounded you won't get an accurate reading.).
Hmmm, what else.... make sure you use thread sealant, but its recommended that you DON'T use the tape, but instead the paste stuff. I'm not entirely sure why, but i suspect it might be a way to help make a better ground contact, but i took care of that my own way. Oh and also, the BSPT piece that goes into the block that i got from the place livelyjay recommended kept leaking. I picked up the same type of fitting from the speed shop where i got the hose, and it worked well. I dunno if all the fittings have sealing issues, or if it was just that one, but be aware that i had a problem right there.
okay SO.....
heres a general shot of the whole assembly, mounted on the back of the intake manifold support bracket. You can use the location and orientation of the oil filter to help get a rough idea for comparison on your car...
and heres a shot of sorta where the hose is running, you can also see my ground wire @ the bolts for the bracket...
and now for where it taps into the block (pic is sideways, again, use the oil filter to orientate). This is where you'll find your stock switch with the green wire running to it. (you can see the stock switch on the lower right, with the green wire running to it.... )
So i know thats tons of info, and i've kind of cut and paste from things i've told people before, so if theres any holes in the logic just ask, i'm more than willing to help out!!
Jason
. Kudos to him/you for finding the right stuff. 
