Ground Strap To Firewall

HI EVERYONE

I'M NEW AT ENGINE WORK BUT I'M LEARNING EVERYDAY.
HERE'S WHAT'S UP WITH ME.

I NEED TO GROUND THE FIREWALL ON MY '66 MUSTANG.

I'M TOLD THAT A COPPER BREADED STRAP IS BEST. O.K. I'VE SEEN THEM.
PROBLEM IS: I'VE BEEN UNDER MY CAR AND CAN'T SEEM TO MAKE HEADS OR TAILS WHERE ON EARTH TO CONNECT THE STRAP?

I KNOW IT GOES FROM THE ENGINE TO THE FIREWALL.

BUT WHERE AND HOW ?
I CAN DRILL HOLES AND CONNECT A STAR WASHER TO A SHEETMETAL SCREW IN ORDER TO GROUND THE FIREWALL ~ IF THAT'S THE PROPER WAY I BELIEVE.

BUT AGAIN JUST WHERE TO DO THAT ? ? ? ?
PLEASE GIVE A GUY A HAND.

THANK YOU ALL AND :whacked:

Anywhere on the firewall will work. Just make sure you know what's behind the wall before you sink a drill bit. There may already be a hole in the firewall that you can use by attaching the ground cable with a bolt on the engine side and a nut on the interior of the car. Then clean all the paint off about the size of a quarter. Once you've secured the strap with the screw, squeeze some RTV all over the connection to prevent oxidation. Connect the other end to either the head, manifold or block in the same manner, except you'll already have a blind hole. Just use the proper threaded bolt to attach the cable.