I’ve already posted about making this boiled wool version of the LB Pullover from Paper Theory.
https://papertheorypatterns.com/products/copy-of-lb-pullover-pdf-pattern
So I thought I’d show how I applied the sleeve facing without creating too much bulk under the arm.
I cut 2” strips of the fabric without shaping them at either end.
Then I lay the strip right along the arm leaving the right angle as it was. So the sleeve facing does not go all the way under the arm. I think the pictures show it better!

I then stitched the facings down and then sewed the side seams. I sewed down the small bits of seam allowance across the top of the side seam. I also sewed down the seam allowances at the bottom of the side seams when I was top stitching the hem.

The trousers in the pics are the Glebe Pants from Muna and Broad in rigid denim.
https://www.munaandbroad.com/products/glebe-pants
The stripy top is an old ready to wear.

All the boiled wool, apart from the grey, came from http://www.quiltyarnstitch.com