I personally would say upper blue above 600 is solid 3+ w/ a couple of 4- spots. Pretty continuous once you get into the rapids, super mellow flat water in the beginning. Also for what it's worth CRC puts this run at 4- over 600. I could see 747 getting exciting... Just don't want a solid 3 boater heading in there w/o a head's up, i think they'd have there hands full. I would say this run is a good half step up from bridges at 2 feet, except the killer bridge move.
Just my two cents...