I know I'm a little late to this thread and Warthog has probably already done the hole punching, but I just figured I would throw in my two cents just in case anyone else happens upon this thread with the same question.
I use knockouts and holesaws all the time for work, and what people need to watch out for when buying knockout sets is they are typically developed for the trades. Often when a knockout says 1" the actual outside diameter is 1 3/8". This is because the 1" knockout is based on the NPT or national pipe thread size, relating specifically to a 1" pipe which has a larger outside diameter than one inch.
You can find knockouts that are sized as what is written, you just have to pay attention to the packaging.
When drilling a round surface I would highly recommend using a hole saw. A punch will want to flatten out a spot in the pot, though I think it would be mostly superficial and not damaging in any way. Just run the drill in a an extremely low speed and stainless is a b**ch to drill due to the nature of the metal.
Either way everyone, have fun with the building.
We learn best from our failures, not our successes.