I’ve heard mixed opinions on a 27 tooth front sprocket requiring grinding to fit.
Mine needed it, the chain was eating into the case and magneto cover when I test fit it. So, me and the Dremel had a play date.
It wasn’t bad, and I was able to save enough to keep a barrier between the filthy chain and the magneto. I would advise taping and covering up everything you don’t want powdered aluminum on.