Well, the easy button is to buy sensors direct from Race Technology, complete with the harnesses and already-programmed-in functions/formulas.

Oil/ Fuel Pressure - http://www.race-technology.com/oil__...ure_8_976.html
Oil/diff/water temp - http://www.race-technology.com/water...ure_8_973.html
Water temp - do you have the OBD inputting to the DASH3 so you can set alarms? If not, same sensor as above.

My oil temp sensor is screwed into the oil pan; water temp is screwed into the head (drilled and re-threaded the stock hole); oil pressure is tee'd off a braided-steel line mounted to the firewall, with the other side of the tee going to the stock dash idiot light. For temps I'm using R-T sensors; for pressure I'm using the lesser-expensive Autometer oil pressure sensor, as pressure is a straight linear-voltage function (temp sensors require step-down resistors to convert the output. Not difficult to do.)

GA