The replacement pcbs don't have cylinder selection, it's not needed. Simply calibrate with the correct frequency for the amount of cylinders. In your case as above for 8 cylinders.
Factory tachos from that era are not perfectly accurate, but were close enough for flogging around the streets.
That's why the manufacturers refer to them as RPM indicators.
I guess a philosophical view would be that if you're going down the road revving at 6000rpm, your eyes should be on the road, not the gauges, or learn to shift by ear.
