The thing that gives those shapes balance is the position of the strap peg versus the fretboard. The balance K puts that strap peg somewhere around the 14th fret, I believe. Anything you turn into a traditional singlecut is going to hurt the balance. Now, if you're talking about one of those modern singlecuts, like a Benevente, that would probably balance okay. They look awfully heavy to me because of all that extra wood, but I've never held one.