I've got a Catto 3-blade FP on my -7 and my numbers aren't that much different from what you're seeing. At altitude I routinely cruise at 2650 and see 168 KTAS or so, with a lot more throttle to give. For a short test, I ran it full throttle at 8000 ft DA and it will do 183 KTAS but at 2800 rpm (obviously above engine redline, prop redline is 3100 rpm). Static is around 2300 RPM.
Point is that of course an well designed fixed pitch will go as fast as a CS, just at a different RPM depending on the pitch. For my typical mission the Catto is a great prop with nice balance of take-off, climb and cruise performance ...but I am one of those currently picking up soda cans on the side of the road to put towards an eventual CS upgrade