What is this opening for?

Thanks Memike. Right next to it on the right, I believe I have the correct gas pedal assembly and the oblong plate with three holes that bolts to the motor side of the firewall. I bought this as a basket case and is my first! Lol, so I'm trying to piece it together. Plus, I had the throttle cable and assembly mocked up maybe converted by a previous owner. Maybe paint and a grommet to keep the opening available!
Thanks again

Sounds good , mine was dun under a shade tree :glasses7: if you like I can get on my computer and show you a picture, I used a home light fixture attaching plate :D
It's been staying busy for 5 years and 15.000 miles of Arkansas roads :D