I think my tack is going bad in my 90 gta. The fuel gauge says 1/8 when it's empty and m oil gauge is always past 80. Is this right..?! If not. Is there any way I can swap it from te existing 120mph to a 145mph one without any issues at all?

 

If you have a a wiring or sensor problem ,then swapping the cluster won't help.
You need to work out WHAT is wrong 1st
Tests need to be done

 

Then where do I start? How do I go about that