Will an instrument cluster from an LS that has the tach work in a non-LS Lumina? Would the correct wiring be in the dash of the non-LS for the LS cluster? Wher is the sensor for the tach? What about the odometer?

Yes, they're interchangable..to a degree. Ensure you get the correct shift display (for a column or console) and the ODO is your responsibility; most states require you report any discrepencies to the DMV, however its illegal to tinker with it anyhow. The tach reference is a white wire coming from the ICM to the dash connector.