The size US 3 (3.25 mm) needle should be is circular needle no more than 16” (40 cm ) long

You will also need a cable needle.

Finished measurements:
Width at back underarm: 17(19, 215, 23, 25)“ 43.5(48.5, 5,4 59, 64) cm
Finished length: 18.5(19.5, 20, 21,21.5)” 47(49, 51, 53, 55) cm
Sleeve length to underarm: 17.5(17.5, 18,18, 18)’ 45945, 46, 46, 46) cm