68 Hood Tach harness
 

Believe me, I spent an hour searching for threads and no luck. I guess I don't know the correct syntax to narrow down a search.
Anyway would someone please post a decent pic of the underside of the hood tach harness mounting location and layout of wire to coil (I believe the ground goes to the reg. mount and the 12V+ goes through the grommet where the vacuum hoses come through) . I don't want to drill any un-needed or incorrect holes to mount the Christmas tree stud (repro tach) to the hood.
Thanks.

Use the search words,( hood tach wires) there is some info.

No pics for you but will say the 68 hood tachs had no 12 volt supply like the repops. 3 wires. Ground, at firewall as you say, coil wire and the grey light wire that went through firewall (at the grommet you should have where the orange wire that feeds your vert top goes through) and connected to the dash light harness so the tach lights would dim w/dash lights. The repop w/12 supply wire that you would run thru same grommet as an original tach will keep the lights in tach on all the time day or night and believe some makers do offer a kit to allow you to dim the lights at an additional price. So both original and repops are 3 wire tachs but difference is 12 volt supply and no dimming of lights. Oh and you'll love a hood tach.