Bulkhead plug for 1.25" hole?

I have an aluminum kettle I used for a home-built electric brewing system. The water heater element I used required a 1.25" hole.

Fast forward a few years and I bought an Anvil Foundry and want to convert my old kettle back to one I can use for occasional propane BIAB batches.

I've searched online and don't see any off-the-shelf options for Bulkhead hole plugs for a 1.25" diameter holes.

Anyone know of a place that sells these or how I can build something myself using items from the hardware stores?

Thanks.