I'm starting to plan out my cyclocross bike for the fall cross circuit that takes place here in and around Ottawa. It's going to be my second year doing the series. I race in the novice level. Last year I did half of the races on my touring bike, and the other half on a converted mountain bike. This year I'm going to use my new 29er, a rigid voodoo dambala. I'm having a difficult time decided what route I want to take regarding tires and wheels.

The current wheelset is built up with Mavic A719 rims. Last year when I raced on my touring bike, I also road on A719 rims with some 700x35c (I think) cross tires. I didn't like the setup very much, I found the rims were too wide for the tires. I found they made the tires wide, but if you dropped the pressure to smooth the ride, you would quickly be bottoming out the tires on the rim. Not fun! So, I think I have two options:

a) ride the rims I have now with tires in the 700x40 to 700x50c range

or

b) build up a set of cross wheels (open pro or cxp33's) and run normal cyclocross tires

I've done some research, and it seems like there aren't many racy tire options for a, so I might go the wheel build route. Suggestions? If I go the wheel build route, are open pros/cxp33's a good width of rim? Too narrow?

I'm also considering changing the crank on my dambala. Currently I a nice but heavy Race Face Atlas 175mm crankset on there. I'm thinking of going to 170mm for more ground clearance and to make me spin more...