Have a look at Auto Meter , Stewart Warner, Datcon Instrument Company (later renamed to Maxima Technologies).

Senders for pressure and temp are a minor part of the system and changing them to match the gauge is easy.

If you want to use Mercedes senders look in a shop manual and see if it shows resistance Vs pressure ( or temp ) they get a gauge to match.

A tach is semi universal needing the negative side of a ignition coil. A coil on plug system might need a converter but given these are so common these days I'd expect some tachs to have this built in.

A speedo can be more difficult if cable driven as not only do you have to match the cable type, you must match turns per mile. A more direct route would be an electronic speedo reading from magnets on the drive shaft , tapping into a abs sensor or even the trans output shaft speed sensor.