You need to move some wires.
But rather than disturbing the harness connector (and moving the pins around), it is often quicker - and way easier - to switch the inputs by cutting and re-aligning the leads that feed the connector.
Pin outs for an 82 with base cluster:
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Pin outs for an 82 with gauges (with & without tach):
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Apologies for the quality of the dwgs - but if you look at the lines going into the connectors you can read the color/number designations.