1993 Instrument Cluster exchange

I know there's some talk on this subject, but I didn't really gather the answer I was looking for. First, I have a 1993 k1500 that had the 4.3L V-6. I just put in a V-8. Will the gage cluster for the V-6 work fine and give accurate readings on everything? Second, the temp gage is bad so I'm thinking about replacing the cluster anyhow....so, has anyone put a cluster with a tach in a truck that didn't originally have one? Did it work? I know that there is a wire plug on one of the harnesses above the block that has a signal for a tach. I plugged into this wire with an aftermarket tach to troubleshoot some stuff previously. Is there a wat to connect the tach from the new instrument cluster to this wire? Or is it already wired into the system? Thanks guys-