By following the line from Sedalia to KC on Bing maps and then going to Google maps and using the terrain view, it looks like th eonly really “hilly” areas are around Knob Noster.
Are you going to run the line through Lee’s Summit? That is the highest elevation in the state, otherwise its a mostly flat area between KC and Sedalia. Also, what time period are you going to do? If you go through Lee’s Summit that is a good spot to scenic your layout. If you are doing a modern layout, Knob Noster is home of an Air Force base (stealth bombers). Also, if doing a modern layout, Sedalia just rebuilt thier Depot so that it is friendlier to AmTrak traffic.
Try going to this website: http://www.mytopo.com/maps/index.cfm. You can browse free topographic maps, although your ability is somewhat limited with a free account. You can pay for a membership, which basically gives you unlimited access.