Greg Williams is right; an AC/DC signed guitar like this is RARE—except all the fancy forgeries you see in fancy frames marketed to inexperienced collectors.
And getting a documentation if you can from his widow is a great idea. She may have a photo of Michael Klenfer with the guitar, which would be the best evidence. Did the drumhead come from her? This may be her on Twitter: https://twitter.com/carolklenfner?lang=en
That looks like her. I have seen pictures of Michael Klenfner with his wife and from what I can remember this looks like her and in his obituary it mentions his wife's name is Carol. I will reach out to her and see if anything comes of it. Thanks for sharing this information.
I'm convinced, congratulations on a nice piece.
me too congrats! that’s the way to prove the questionable ones!!