I dont have any diagrams to assist, however, for power, use a 12v test light and look for a source that is hot with the key on and use an inline fuse to protect the circuit. I would probe fuses to figure out what circuit is best to tie into.
The draw from the tach should be fairly minimal I would think. I would think you also need a good ground wire location, find a bolt under the dash somewhere, install a proper connector and be sure its clean.
Lights, I'd pull the headlight switch out and see what color wire is for the parking lights and tie into that somewhere where you have access and can make a proper (clean/neat) connection.
Lastly the coil, check your install instructions for the tach but I believe most use the negative side of the coil, which from the days I installed autometer shift lights in every 5.0 fox body I've owned, SHOULD be a green wire, but do double check and confirm that.
My 87 GT is no race car so I haven't put one in it....yet May have to at some point just for nostalgia sake. Lol.
Above all else, take your time to do a clean, professional install, use wire ties to secure the wiring and route everything so it looks good.
Some of the great folks on this site have a copy of the Ford factory electrical manual, which would show you the wire color coding and circuits. Maybe someone will post a link to that. My Haynes manual has some limited wiring schematics I've used to help me over the years also. I believe it includes the lighting circuits and ignition circuits, so you could find what your looking for that way also.
thanks for the info. just need to make sure i hook up to the coil right it has a connector no terminals so it’s throwing me for a loop i have what’s looks like a solenoid that is mounted on the frame near the battery with two terminals coming from the coil but want to make sure i am hooking it up right for the signal so anyone with pictures would be great! thanks all
The above posts are correct
The lights wire you are looking for is light blue with red hash stripe
The tach wire at the coil you want is the green with yellow one