hi new to passion ford after getting my hands on a sierra saph with a 2.9 24valve cossworth engine,

my question is, and im sure its been asked a few times before and i have looked, but could not find.

but can anyone tell me where to wire a stand alone rev counter??
the car has not got one, hence why i bought a stand alone one, i have tried taking a feed from the coil pack but it just dont seem to read right, is there anywhere else i can take a feed, or anything can do??

and it has the wasted spark system on it, (coil pack)

any help would be great,

thanks