help installing sport comp tach in 95 gt

hope you can help....ive been installing my new tach in the car and i ran into problems on where the green wire hooks up.....it says the negative on the coil.....well i have a crane cams P591 Fireball coil which is basically like a stock replacement, and ive been having trouble finding the negative....also i am debating where to put the wires thru the dash......hope someone can help cause im bashin my head against a wall like this dude.....

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95 Mustang GT 5spd
Flowmaster American Thunder cat-back
cut stcock springs one coil
K&N filter
Moroso distributor w/ moroso 8.5 wires
Crane Cams P591 Fireball Coil
a/c delete
Autometer gauges
Simpson 5pt belts

while ur being such a great help.....do u think u could tell me what wire i tap in the dash lighting switch??? and also the one in the ignition switch...thx a lot for the help....ive done a lotta work with my dad on his car but its a lot older (1966 chevelle 10.60 in 1/4) and a lot more straight forward wiring wise.....thx