Because of the large dome on the CTR pistons, you'll defintely want to clay the motor to give you the advance/retard limits of the cam gears to avoid valve to piston and valve to valve contact. You can get an idea of how to do this on http://www.c-speedracing.com under the "how to" section.

What cams are you going to use? I ran Skunk2 Stage 2 cams on about 10.9:1 compression, and they ran fine. They aren't really considered "big" cams compared to some others out there. If you're going to run something huge, you'll definitely want high compression. Read up on static vs. dynamic compression to get an idea of what's going on in the combustion chamber while the engine is running.

Flat valves are nice if you just need a little nudge to put the compression where you want it. They don't offer anything substantial overall, so expect a .2 to .3 bump.