Looking at a couple of cylinders I've got here both have slight marks, but I wouldn't call them dents, surely well adjusted powervalves don't hit the port that hard? Polish it out if you want, I doubt it's big enough to matter.

As for the crack no sane person is ever going to recommend on a forum that you run a damaged barrel but we all have.

If you can feel it at all yes, get it replated for sure, if not, well....it's up to you.
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Please do not PM me technical questions, if you can't find it on the Forum start a thread