Kansans are a heck of a lot more likely to elect a Democrat Governor or AG or to some other state office than to the U.S. Senate. I don't see why Kline having a tough reelection fight for AG means that he wouldn't defeat Moore handily for the Senate. Remember, Kline nearly beat Moore in 2000, and Kansas as a whole is 6% more Republican than the 3rd CD. As for Ryun's religious conservatism "not playing well" in Johnson County, that's as may be, but I haven't seen any Democrat defeat the equally socially conservative Sam Brownback for the Senate.
And if you don't like those two candidates, how about Congressman Jerry Moran? I doubt Moore would even approach 45% against him in a Senate race.
Unless he loses. Morrison has a solid reputation in Johnson County and the ability to pull disaffected Republicans. He also has a boatload of cash. And if Kline has problems with state-wide office like AG then what makes you think that Senate would be any better?
Ryun is a flake and he could be vulnurable because you know the Democrats will raise the issue of his townhouse purchase back in 2000 and try to tar him with his connections with DeLay. Moran would have a better chance at keeping the seat should Roberts retire. Failing him I'd pick Tihart over Ryun. But in either case if the Kansas GOP keeps fracturing the way it has been then any Republican will have to work harder than he should have to.