i have converted from 2.8 V-6 to a 350 V-8 a 89 firebird what do i need to do to make the tach work correctly. thank you for your help.

You will need to replace the tach in the cluster with one from a V8 car. A typical non digital cluster (you won't be able to buy just the tach) price from a junk yard is about $75.

thanks again for your prompt reply.