Bob, Ive fished my local tailwater for striper with a fly rod for the past 2 or 3 years. Depending on the average size of the fish on Norfork and the size fly and the distance is all something to take into consideration with the line wt. Well start with fish size,1-10 or so lbs Id say a nice 8wt but if there are larger fish on average say with an 11-20 on average go with 9wt +
Now fly size, If its around 2-3inches long all you would need is a 7wt. If its between4-7 id say and 8 or 9wt if larger go with a 10wt. Also take into consideration the materials of the fly. I like to fish synthetics and bucktail... They might not have a good movement with them but even with a clouser out of a synthetic in shad coloration with the bass on top they wont care and they will hit something thats tossed in their face.
Action of the fly rod, I figure most of the fishing there is on a boat, if im wrong please correct me, but the distance wont really matter. Most distance is from the anglers experience. Also the faster the action means the tighter the loop. Slower action=larger loop but sometimes at short distances I can get a tight loop. Medium action=mid range loop and a Fast action means a pretty tight loop.
Another factor on your loops is line wt. if the rods overweighted its more than likely going to be slower action. same thing with a sinking line. if its underweighted then the loop will be tighter. If its an equalized setup then it will all depend on the action of the rod... I hope some of this will help on your line wt and decision. Give Bill Butts a PM and talk to him about it... He is a very knowledgable person when it comes to stripers. Good Luck!