First, the destruction of that yellow is disgusting. Second, the problem with the kettle lid, is that it doesn't hold the heat. It allows heat to pass though. The reason for putting the cast iron on the top is to retain the heat. You can also use another pizza stone on top. It needs to be something that gets hot and holds heat. Why the hell would you cut a hole, just lift the lid a little bit. I understand if you just want to do some project, but why destroy this stuff? Especially a classic. I know he was to stupid to know it was a classic, but it looks like the work of a hack anyhow....
Brian