I'll need to watch my video of him against Canto again, been ages. But it really impressed me, and Confuscious post re-interested me in Park. The first Oguma-Park fight was really decisive though, I was surprised they had two subsequent fights after it. Oguma just walked right through him and landed everything before KOing him. Could anyone win more decisivly and be beaten (arguably) in a rematch?
Even past prime, Gonzalez would have indeed given him a lot of trouble. In fact, there was much talk of a match with Tae-shik Kim back in the day in Korea, and domestic experts actually thought it was a pick'em type of a fight. I think that tells you all of Park's limits.