I used a US size 8 needle.

Warning: Some of the math does not work out in the neck shaping.

Here is what I did:

Back Neck and Shoulder Shaping:
I worked across 15, BO 39. At this point, I’m not sure if it is just me, but it seems like the left and right front are labeled different than what I am used to. (I always thought it was “as if you are wearing it”). I did the decrease row to end with 14 sts for each shoulder to do short rows.

Front Neck and Shoulder Shaping:
It seems to me that the short row shoulder shaping needs to start at the neck edge like it did on the back piece. I think that is what I did to get the correct slant.

I have full arms. I made a larger sleeve and casted on 68 sts. I shortened the sleeve and had to change the sleeve cap to make the sleeve fit into the deeper 8” armhole that I made. I decreased every RS row 9 times, then every 4th row 5 times. Bo off 3 sts at the beginning of the next 2 rows and ended up with 19 sts that I bound off.

I hope this information helps someone! I love the result.