Harry Morseth was one of the giants of American custom fixed blade knives and is very collectable. I don't collect Morseth but have seen quite a few and I would not buy that knife as a Morseth. I expect one of his knives to have a sans serif marking on the ricasso and parallel to the hilt. I also expect a different spacer stack and more evenly shaped handle. Lastly, that sheath is not one of his patented Safe-Lok sheaths which would be a must for me. Could it be real? Perhaps, but I'd defer to more knowledgeable folks. This is all before we get to the after market "improvements" to the blade.
AG Russel did buy the name from Morseth's son sometime in the seventies but I am not familiar with any of the knives and sheaths Andy put out under the Morseth name.
One of the best knife shows is the Oregon Knife Collectors Association meeting in Eugene and you may be pretty close(don't know your area). You just missed this year's show but if you take that knife(or any other knife) to the show next April you'll get all the info you could want.
Bob