You should note that those oil pressure transmitters are mediaeval in their design. I pulled one to pieces, it's basically rheostat with wiper arm operated by a system of levers.... archaic! The on the other hand ive got installed now seems to somewhere near, +/- 15% on a good day. Installing one could cause you more consternation than you need. Ive had a normal bourden tube gauge that i knew to be accurate to within about +/-10%. But hey, it keeps the car complete. Dave, do you cars not have oils pressure indication?
By the way I did install an oil temperature gauge, the sender I installed an tapping already present in the Raceline sump although I installed a 2nd transmitter up near the pressure take off with option to use. Mine's the Mazda MZR engine by Omex, as per the Plus 4 SS, but to all intents and purposes a Ford Duratec.