getting into the s12 game

What's up guys I've been using this site for a bit without introducing myself, so hello! I bought my s12 a few weeks ago with the intent of drifting it. It was already gutted and had a harness bar and bucket seats put in, as well as a welded diff. Issues I can't figure out are the Speedo doesn't work and the tach jumps around and sometimes doesn't work, but I know this isn't the board for that discussion but if you know a fix for that lmk!
EDIT:
It's an 88 notch, sorry forgot to say

Welcome aboard! There should be a thread around here somewhere explaining your issue. As start have you checked the connection to your coils? There is a tach that leads to one of them primary iirc...