Aftermarket Tach install ?

[smorg007]

I finally gave up and purchased an aftermarket tach conversion upgrade for my 72. It installed in the cluster gauge without cause or concern and looks great. I have two questions;
(1) Next step refers refers to using the existing 3/4" hole in the firewall or if you don't have this hole "DRILL IT". Problem is it does not say where this hole should be drilled to match factory placement.
(2) The supplied wiring diagram shows connecting the brown wire to the negative side of the coil with the supplied eye connector. I have an HEI distributor so I don't have this type of coil. My HEI distributor has a male spade connector on the cap for tach, so I assume I can cut the off the supplied eye connector and replace it with a female spade connector and connect as though I was connecting to the neg. side as coil?

If someone can post a picture of where this hole is in the firewall I would appreciate it and let me know how to connect to HEI so I don't damage my hard spent investment.

Thanks in advance.