I have to second Run2Catch, the river is a heck of a musky fishery. the biggest problem with the river in the spring is one day the river will be at normal height and the next its 7 feet higher and unfishable.
I fished with Red last year on the river and had a great time. I would definitly recommend him, you will not find someone more knowledgable of the river than Red. He also does trips on Kinzua and Tionesta. When we went the river was high and muddy so the fishing wasnt that good but we did manage 3 pike.