Your gas gauge is electrical.
If you are all mechanical except the gas gauge, you can do like Carl or buy this.

You will have to tell us, if you have mechanical. As said, if the under hood sender has a tube instead of a wire, it's mechanical.

The 305 V8 would have electrical senders. So if you have original gauges, someone had to adapt 1948 to 1973, and up, compatibility.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn