Like the others said, you can use the factory temp sender for the temp gauge, then tap into an oil galley for oil pressure. The ammeter is better replaced with a voltmeter which can be had out of a square body truck, or Tbone sells a nice kit for it. As for the tach and speedo you could use a Dakota Digital SGI-5E which is a CANBUS interface that puts out signals for tach and speedo. Then you could get a Dakota Digital speedometer converter which is a box with a motor that spins the factory speedo cable, or you can convert the speedo to electronic which is what I do.
http://67-72chevytrucks.com/vboard/s...?t=512751These