If the drum is out of round, you can lay it on its side and try to find the off sides and with some pressure get it back to round.
As for the lid, there are all sorts of methods. One is the flange method, but this requires you to sacrifice the bottom bowl of the kettle. I had to pound the edge of the kettle flat and then weld it onto the lip edge of the old drum lid. Another method is to make it so the lid slides or fits inside the rim of the drum vs over and around the outside, the way it fits on the kettle bottom.
I'll try to find some links for you.
Bob