If you watch eBay etc you can find NOS gauges for a reasonable price.
Realtime engineering
RTE limiter - rte makes a great IVR.
Replacement cir boards are available.
I sell a gasket set for 67-71 dart clusters.
The temp sender is easy at the auto parts store.
The tough one is the fuel sender NOS can be had sometimes, rebuildable used are available, aftermarket suck but others have said a "Metermatch" helps.
As for senders that can run two gauges, not likely, the oil pressure can be "T"d, water temp can have alternate sender location so you can have 2 senders. Again fuel will be the tough part.