Ok, as for the plugs, they are the same, assuming that both gauges are from the same generation 4Runner, in your case, 1990-95. But, if your '94 did not come with a tach from the factory, and you are installing a new inst. cluster that has one, then you will need to locate the Black IGN+ Signal wire from your Ignitor, and add a wire to it and route that to your C plug on your inst. cluster, usually in position 11 or 12 I believe.
Check a wiring diagram and look for the Ignition Signal wire (IGN+), which is Black (with no stripes) and runs from your Ignitior to your ECU.
Everything else should work ok, but what about the Low Fuel Level Indicator light? I don't believe non-SR5 models had that on the pickups, but I am not sure about the 4Runners. If your 4Runner does not have it, then not only will that circuit not exist, but also you would only have a 2-wire fuel pump sending unit.