I started out with calculations from Ann Budd, but with the back-neck-shoulder short row shaping from KMBOMT.
Kept on going with Ann Budd to the bottom of the armholes.

Smaller needle for bottom rib, neckline and sleeve rib.

Tried with neckline trim in pattern on 2.5mm needles and 100 stitches. Too narrow. Will have to try with either 110 stitches or slit a Henley.

Ended up doing both. A henley and 120 stitches. Folded over and stitched down. Very happy with the outcome here.

Used a 11 st i-cord for the button band. Split this in two smaller i-cords over 3 rounds to create vertical button holes.