I was trying to determine that too when I did my swap. So I wasn't doing a restoration I wasn't too concerned about absolute exact but as close as I could. I located mine at the 1 o clock mark from the gas pedal and about Two inches measured on the tunnel off the firewall. I don't know if this is what you're looking for. GT22 should know exactly.

 

Everything in your pics are pointing in the right direction. There is suppose to be a dimple in the metal where to drill.

 

64-66 V8 4-speeds were all the same, but located differently than the 64-66 I6 4-speed.

 

It looks like I'm way off in my car. Oh well.

 

It looks like I'm way off in my car. Oh well. Forget what I said, listen to 22GT.

 

That is exact!

Taking out the carpet right now to hunt for that dimple on an original floor thats been painted over several times.

 

I think I found it!

Does this dimple with a blue circle around it look like the correct location?

FYI my accelerator pedal is unhooked in photo.

I was going to use a 7/8" drill bi-metal hole saw then curved file to smooth unless there is a better option?

 

Looks like you've struck dimple. Your hole saw and file should do just fine.