Qawi beats them both. Qawi wouldn't have to make 175, he could come in at whatever weight is comfortable but the Qawi who beat James Scott and Jerry Martin would easily beat Willard and Carnera. Neither is skilled enough to hit a 5'5.5" man who fights out of a crouch, has an excellent jab and has excellent inside skills. Qawi has every advantage over both of them except for height and weight.
Qwai fought a 6' 3.5" , 80" reach, 240 pound Foreman and managed to tag him quite a bit but Foreman's sheer power was too much .. I see both Primo and Willard being too strong and big, jabbing, hugging and holding to decisions ..