I did this on a 1971 Camaro. The original cluster had a huge gas gauge, no tach and idiot lights; pretty sad for an SS model! I found a cluster out of a wreck with tach, oil pressure, small gas gauge and a tach. It also had a clock. The tach replaced the huge gas gauge and the gas gauge moved off to the corner.
I had to buy new senders for water temp and oil pressure. The senders replaced the switches. Worked fine.
Interesting video for you:
www.youtube.com/watch?v=CkRAGtNdPCs
