I have a 87 iroc carb. motor I just put a msd 6al box an I ran into a problem with the tach it doesn't work I also have a blaster coil an a pro billet dist. I hate to by a tach adapter kind of short on money after buying all this. will I be able to hook it up to the neg. side of the coil without destroying the gage this is the factory gage it has a wite wire I hooked to the msd box could I get some help please what to do. Thank You.