I have a 72 that I'm restoring and modifying. We're changing the sweep style dash to the gauge style dash. I've found several reproduction dash clusters for sale (bought one), but they never offer the wiring harness. I've bought the cluster with all gauges (no idiot lights).
So, before I go tearing my dash apart to change it (I don't want to have a long down time), will I need to buy a different wiring harness, or can I use my existing one? Will I need new sending units?

You will need new sending units. You will also need to modify your exsiting harness to connect to your new gauges. I would consider wiring those new gauges seperately with new wires and not hacking into you original harness.

Thanks for the heads up. You confirmed what I suspected. I'll spare the original harness and install new wires for the gauges.