I sucked it up in the end and charted out the continuation of the colour pattern into short row shaping for the shoulders. It wasn’t so bad in the end and the result makes it worth it. I got my scissors out on Thursday and cut the steeks for the neck- and arm-holes.
I have to say that I deliberated the cutting for at least an hour. If I cut and it was wrong, then it would be horrible, even impossible, to salvage. I might not have enough wool to finish it off. I might run out of time trying to fix it. Obviously, sitting around looking at my steeks wasn’t doing anything to improve the time situation so in the end I just cut the darned things.
…And I am amazed to report that it fits perfectly. Maths actually works sometimes! I’m nearly finished one sleeve and then there’ll just be the other sleeve and the neck band to do. “Just”. Is there a penury worse than ribbed sleeves?