Even though I haven't fished the Missouri Riv., I'm aware of the fast current this river has. I thinking heavy weight to keep the bait down. I would go with the a heavy action rod in you financial standards and go with a ABU 6500 reel. To me this is the best all around reel for catfishing. A reel like this should go for $85 to $95. check out Catfish Connection on the web.
Might as well get a good reel, you can go with an older abu garcia 6500 and up do your research the new chin or pakastan are nt the ones or for the money I used a Penn 320gti and itll holdem pretty well. but I think the cadillac is the garcia ,switserland made,but it is all personal preferance and experience will tell you. Youll need good gears for big cats, some of the ocean reels, research them go to forums and soon youll know what you want.