Ping Kay

I'd take a shirt that sort of fit, except for the hump, and copy the back after marking the apex of the roundness, and also if you need to take darts to the back shoulder or neckline. Draw in the new design line for the yoke, not more than about an inch above or below the apex, and separate the two pattern sections. Add the extra 1.75" to the lower section at the midline, tapering to nothing at the armscye or side seam -- wherever it terminates. The design line can be anything you like -- straight, curved, western shirt yoke, whatever you like.

Copy the upper section one more time, close any darts, rebalance the neckline and you should be good to go. Depending on the vagaries of age and time, you may still want a couple of tiny (1/8" wide uptake, less than an inch long) darts to back neckline, rather than taking all of the darting out in the yoke.

If this makes no sense, I'll do you a quick series of photos.

Kay

I think I get the idea but pictures would help if you don't mind. I'm a very visual person. Juno