I am not familiar with MS cameo coins. I assume you have a PR 69 cameo half dollar. I purchase many PR 69 deep cameo modern U.S. commems from L & C coins. They are fairly common.
Nice coin! Buck three-eighty, sight-unseen, offer good indefinitely--I must have it!!!!!! Check to see if it's the double dye PR. Those are unique because nobody ever heard of them. At the 100-X magnification level it's plain as day on his upper-lip. There's also a misplaced S mint mark on the bridge of the nose that's inverted (not the nose, you big dummy, the mint mark is inverted!). Just look for the dye markers cinching the dye as #15. One is the clash coming off his nostril, N-S (actually, NW-SE), which looks a very lot like a booger. It's not a real booger, just a reasonable facsimile thereof a real one. PM me when you're ready to let this baby boy go...
The coin looks very nice but I agree with Schwa. Something is wrong with the slab/ coin mismatch. I have an 88 proof set, but I am sure my half wouldn't grade this high. But with the slab problem, this coin may not be a 69 DC.