Doug,
If cable travel proves to be a problem, you could always make and insert a simple leverage-changing bell crank midway in the cable run (as I did on a friend's bike) or install a TravelAgent-like pulley just before the rear mech.
These levers are certain worth the effort.
If you can get them to work as-is, so much the better. As long as you don't run out of travel, the smaller drum size will make it easier to engage each gear on the 10 - speed cassette...and it should work a treat on 8. The only problems I've had friction-shifting on 9-speed came from the narrow cog spacing and the difficulty in avoiding ovetshifts. Still, things came right in short order as I adjusted to the shorter throw. With the smaller barrels, these should be far easier.
Best,
Dan.