If you want a pointer to match your existing 71-72 indicator, this is what you'll need.
https://www.ecklers.com/1971-1972-ch...-859074-1.html
Here's the fiberoptic cable that goes with it.
https://www.ecklers.com/chevy-truck-...-178377-1.html
You may also need the bulb socket that the fiberoptic cable attaches to on the gauge cluster.
https://www.ecklers.com/chevy-and-gm...-324634-1.html