5986 is missing its back bodice piece. When I did the test before, I borrowed the back from DuBarry 2477b (1940), which looked similar. At least, the patterns are the same company, similar years, and are both plain backs with ordinary waist darts and no distinctive style elements. It worked, but I seem to have misplaced the traced piece I used (2477 needed to be graded down a size).
So . . . new copy knocked out over lunch yesterday. I did more this time--the lower half is graded down. The upper half, to which I would have had to add width, anyway, was left alone but with a shoulder dart placed to make the shoulder seam match the front. And I added an inch of length. I thought about grafting the neck dart into the shoulder dart. I might do that yet but I don't think it's a big deal.
I need to run up another test and then make clean copies for both patterns.