[MARKDTN]

Just making sure I understand what you want to do; you want to leave the original mechanical oil pressure line and temp sensor for the gauge and add coolant temp and oil pressure sensors that will talk to the Holley computer?

If so, I would leave the original temp sensor alone and maybe the oil pressure too. If you have a port above the oil filter, you can add the oilk switch there. You can add a tee for oil pressure at the back but it's harder with an HEI if you have one. If you have a junkyard with 80s/90s stuff, a van had a nice 45 fitting that gets the original sensor out from the HEI (trucks have them too, just harder to get to). You could add a tee to that and put the new sensor up and the old tube down/back. The water temp is a bit trickier. What intake do you have? If it is aftermarket, you likely have a spot for another sensor drivers side. You could try to put it in the passenger side head, but that plug is hard to remove usually. You could get a later thermostat neck and add the sensor there. You do not want to tee the one in the head as you will not get enough flow and neither will read right. Coolant temp is very important on EFI engine fuel mapping so it needs to be in a decent spot.