Mechanical oil pressure gage help.

My memory from when I last added a mechanical guage to a slant(1999?) was that the oil pump outlet threads are 3/8" npt and most common pressure senders use 1/8" npt. I would not leave the electric sender off when installing a mechnical guage. How often would you look at the pressure guage? That bright red light is very useful for getting your attention and directing you to the guages. All it take to retain both is a simple hardware store pipe tee hanging off the end of the oil pump so that the sender and the mechnical guage hose can both be connected at once.