The gauge cluster in the 86 has issues, just the tacho really. Have had a couple of people look at it and couldn't work out what the story is.
So looking at aftermarket tacho options. Ideally want something 0 - 9000rpm, with a shift light. Multiple shift lifts would be even better, think F1 etc.
Don't want anything overly gawdy or cheap. Just something clean and functional.
Cheers.