Most of the people who I knew that bought new Z28's or L78's did not order factory gauges. Such is the case with my Chevelle too. I did not order the car but who ever did knew what they were doing. L78-89, M22 trans, 4.10 rear, bench seat and chambered exhaust.
That's just they way it was back in the day. One of my best high school friends ordered a new Nova SS L78 when we were seniors. Got everything but factory gauges. Again, if you lived the day back then, ordered a solid lifter Camaro, Chevelle, Nova, etc, you did NOT order factory gauges. They may look nice in today's world of restoration but they did not get the job done back in 1969 when the cars were new. The temp gauge is what we called the mystery gauge. There are gaps in the numbers so you really never know what the temp is.........
Jerry