>Can I use LX v-brake levers on non v-brake cantilevers, specifically
Yes, if you adjust the leverage. They're not the best levers for
doing it though, as the Servo Wave gadgetry isn't quite the same
adjustable pull mechanism as the simpler Tektro or Dia Compe. It'll
give you workable brakes though, you just won't be able to set them as
close to the rims.
Why not buy some new levers ? Round here pairs of old non-V levers
are being practically given away by shops clearing out old stock.
They're cheaper than decent brake pads !
>I am thinking of dumping my LX v-brakes, the pad wear is awful
Shimano pads are crummy, even the XTR. Swap your pads to Aztec first,
then see if that fixes it. Koolstop if you don't ride in rain.
Look at the new Onza Hola too. All the old bits from the HO, with
long arms to make it into a V. Cables like a V, pads like a canti.
I've not worked on one yet, but I intend to use a pair of spare HOs to
make my own clone of this design with some new arms.