Trying to replace my old kitchen gas stove, how to find a replacement?
MAybe you can try with a marine one like one. Or maybe some vintage/antique seller like this one could have one, try asking.

However, I believe that if you want to modernize your kitchen, you'll need a new shape. All that you will find in this shape will likely be vintage.

Alternatively, what would happen if you just put a square/rectangle one on top of the hole?

Hole:



New square fitting:



Added on top:



Finally add some (fake) marble to hide the space below the corners: