Do Campy levers have the right Pull ratio for BB7's?

What tuning can you do to drop weight on them?

Will these rotors work?

http://www.bikerumor.com/2011/12/01/fir ... ke-rotors/

It looks like Tune Prince/Princess Hubs are nice and light at about 270 grams combined only about 30 grams more than Mig/Mag, so assuming an extra 300 grams for brakes, 30 for hubs, 50 or 60 for tougher spokes and maybe 200 on the frame fork, 600 Grams or so extra to run Discs?

If your using postmount brakes, you can use alu. bolts to hold the caliper to the frame/fork. You can also use 3ti/3alu. rotor bolts. Swap any other bolts to Ti. You could also use alloy backed pads, but those are usually organic, which won't last long in mud.

If you have quite a bit of patience, you could sand the calipers down, like this guy:
http://forums.mtbr.com/weight-weenies/t ... 52294.html

Ashima rotors should work fine. If you want the absolute lightest, have a look at Scrub components.

If you wanted superlight, you could go with Extralite hubs to save even more weight over the Prince/Princess, but I don't really know how durable they are. You also don't need thicker spokes. I know plenty of people who use DT Revo's/Sapim Laser on their MTB's, all of them are 170lbs+. I've even heard of downhill racers using light weight spokes (CX-Ray's, Revo's, Lasers, etc.) They may need to be longer, depending on how you had your previous wheels laced, but that will add very minimal weight. IME 2x non-drive side front, radial driveside front, and 2x all the way on the rear will be fine.

So you're going to spend a lot of money to get your bike 600gr heavier.
I wouldn't do that eve if all the stuff comes for free

The disk hubs are for mtb and they usually are 135mm. I'm not sure if your frame is 135mm or there are other light options for 130mm, if this is not the case you should go for something else (and probably heavier)

In your estimation you should consider the extra weight that comes with longer cables and housing to reach the disk brake.
The cable housing is going to be 1mt longer

In my experience, running Centuar with the road specific BB7s, they don't have enough pull to get the brakes set up properly. Braking performance was so bad I gave up on cable activated discs and have gone back to cantilevers, and this was despite me investing a lot of time and effort in optimising the setup.

So Campy Levers have a lower pull ratio than SRAM or Shimano?

I had BB7's on a Cdale Cyclocross Disc 5-6 years ago with Dura Ace 9 sp levers- it was amazing.

Frame will be custom to accomodate.

I know this is weight weenies, but sometimes (rarely though! ) the added performance is worth the extra weight! Other than the rotor, it's static weight which doesn't really matter a whole lot in cross (in my opinion).

Campagnolo and SRAM both have the same cable-pull - I've had absolutely no problems running BB7s with Campagnolo Ergos in the past

_________________
Just ride

There are road pull ratio BB7s and V - pull ratio ones. My suspicion is andyp was trying to run the V ones with a road lever

_________________
Success is how far you you bounce back up after being knocked down

Your suspicion is wrong.