Passenger of size question

Please be kind as im new to this. My husband is a passenger of size 6'6 and 400lbs, so we bought a whole row (3 seats) on economy for me and him on our flight from honolulu to guam (7 hour flight).

I saw that I can upgrade to premium plus for 30k miles each person. Is one seat on premuim plus be enough space for him

Or keeping the row in economy better