I was given an old Honda generator that's in pretty good shape, except the gas tank was unsalvageably rusty. Luckily, I was able to order a replacement tank, but it has a hole where a fuel level meter is supposed to go. Unfortunately, the meter mounted in the old tank is in pretty bad shape too, but I can't find that part available anywhere.
I'm not that concerned about not having a fuel meter, but I need to do something about the hole for it. I put a picture below for reference. It's a metal tank and the hole is on top, maybe 1 to 1.5 inches in diameter. In the picture, it's the hole on the left.
What can I do to patch it?
Here are a couple pictures of the old part:


