If you really want something with no rust I think any used tank will have some surface rust on the outside I will take a look at mine and get some photos.
I know the fuel sender in this car was totally rusted out. I had to drain the tank clean it and install a different fuel sender to get this particular car running before I got it running before its tear down.
Good thing is the tank is not ZR-1 specific any C4 fuel tank will work in your car.
zip says they have it in stock
https://www.zip-corvette.com/84-96-gas-tank.html