Got gauge with US 5/3.75 mm needles.
Went one size up (XXL) for the sleeves, they came out exactly right.
Added one stripe to the body, to accommodate my longer torso.
Instead of after-thought buttonholes I went for 6 of Barbara Walker’s self reinforcing buttonholes in row 5 of the button band.
The sweater is a bit bigger than planned and it tends to slip off my shoulders - overall I like the result though.
After washing and blocking, the sleeves grew quite a lot so I will wash it a again and give the cardi a spin through the dryer. As this is Lana Grossa superwash sock yarn there should be no felting.