I spent yesterday's lunch hour tracing the yoke pieces. The pattern is cut to a size 10 but he original owner was kind enough to save the cut-off slivers so I could piece them back on and salvage the other two sizes.
The sleeves on this thing are enormous--the finished circumference would have been 19 inches at the bottom. This is just too much for me. I forgot to bring pins and I didn't want to go to the trouble of tracing, cutting, and taping an interim copy of the sleeve, so I folded three tucks into it and secured them with paper clips at each end. I used the lengthen/shorten line to keep the tucks straight and measured them to make sure they were a half-inch all the way across:
I traced it to a size 12 and re-drew the sleeve cap, lowering it about an inch as I went. I need about six inches to go over the top of the armscye seam and this still leaves me a little over eight, so it's fine. This should make it a bit less puff-sleeved, too, without shortening the sleeve.
You can see the difference between the two:
The arm part of the new sleeve--the part below the armscye--isn't shorter. It looks like it here, but its not.
This pattern also recommends the weak sleeve finish that I used on McCall's 4866 (1975). Reducing the sleeve width will make it easier for me to do a regular placket (I'll probably just do a continuous-lap placket).