Autometer tach and boost gauge questions, almost done

[1993SSP]

Where is the best place to put in the T fitting for the boost gauge?? Also which wire on the coil is the negative for the tach, these are the last 2 things I need to finish up

 

[89-notchback]

Not sure on the coil i think they should be marked negative and positive, for the boost guage you want to use manifold vacuum, so T it off the manifold somewhere.