Sorry, I'm still trying figure out mixing the 10 and 8. The cable pull is right, but presumably this means that two gears on the shifter simply won't work. On the loose end, this may not be a problem, but if you ever try to overtension the cable (shift to a low gear that your limiter screw won't allow), you could find yourself with a broken shifter. Campys are supposed to be better in this regard than Shimanos, and my experience with breakage is Shimano, but it still seems like a risk.

If you go ahead with this, make sure it's the low-tension gears that are beyond your shifting range.