I have a Sirrus Elite disc with an 11T-30T cassette 9-sprocket that needs to be 34T or 36T low end in order for me to climb Seattle's hills at an 80+ RPM. I'm thinking of switching the rear derailleur to a Shimano SLX and finding a cassette 9-sprocket that will work with my OEM Sora 9-speed shifters. I would need a longer chain too for the larger gear. Is their a 9-speed sprocket available that goes from 11-36T or 34T?

Lars