Enviroguy; that neck does look good on the Buescher. As you know, and most likely which is why you chose that neck, the original was under-slung too. The Buescher neck did have the extra wire braces under it, but the Yana neck preserves the right appearance of the horn. That looks like a pre-'Selmer Buescher' if I'm seeing it right, which was a very fine tenor. Even if it is a post-Selmer acquisition horn, they can be great too. I played one for a few years back in the '60s. On tenon sizing, I know that new Selmer necks are routinely sized-up for pre-'67 Selmer tenors with no ill effects. The real worry in the mechanical sense is the 'work-hardening' that occurs from working the tenon, which causes it to be more brittle and possibly crack. On the other hand, Selmer and other premium neck tenons are higher-strength bronze and can take more abuse than some other alloys. Ideally, a sized-up tenon should be taken off the neck and properly annealed which would restore its ductility. This of course would take the finish off the tenon and part of the neck, plus I don't know of any repair facilities able to do this. Cryo treatment would not help - it would have to be heat treated.