i may only put a tach in for temporary use. like to have an oil psi gauge in the car. i need it small and out of the way. Jamie doesn't want any gauges.
Autometer makes a very nice white-on-black 1 1/2" oil pressure gauge. Not cheap. Mechanical.
They also make even smaller triple guage setup, all electric. They don't look 70s however.
Have you thought about a 2 1/8" gauge pod for the A-pillar? You could get a 2 1/8 tach for there too.