Stay true to yourself and disclose if that is your nature. Someone will come along. If you tell them everything, you're not going to have it eating away at you wondering if you should have said something. Sell it with a good conscience. I sold a bike a couple years ago and disclosed everything. Even took close-up pictures of the damage from a crash. The buyer appreciated the honesty and I knew he knew exactly what he was getting. There were no surprises for anyone.
Also, if the person that buys it is going to use it for CC, then they're pretty damn dumb not to run a few hundred rounds through it to make sure it functions properly before they start carrying it.