Here's my thoughts and both revolve around the events of Day 5:
The reason I think North is innocent is the fact that he has a decent (but not perfect) record for voting mafia. That suggests that he might be a regular innocent or priory with no invest powers. He actively was involved in voting out oldman (runaway) but also Clonies and Michael. On day 5 specifically was the day the head mafia was voted out. I'm not sure a mafia member would go through with that. That leads me to the reason I think SCNCY is inno.
On day 5 with Michael up on the block, SCNCY was the other option that drew significant amount of votes to compete with him. From my list of people that I list as suspected mafia, there was a concentrated effort to save their head mafia. Could mafia have been sacrificing one of their lesser members? Perhaps, but I think that is incredibly unlikely considering at that point they had already lost 3 members in the first 4 days.