I've flown with SAS a lot, (and Norwegian a bit), often on small planes with restricted space.
If those are your absolute max dimensions then I'd say you'll be OK.
I sometimes take a 50cm x 40 x 20 rollaboard on with no issues

If they don't like it, they might take it off you at the boarding steps, but even then it will be handed back as you disembark.
Never happened to me but seen it happen to others.