+1 on Brian's post. If you went indexing, you'd have to alter the backing plates of the shifters to fit over the bosses.
Been there, done that, on a 1986 Cilo with SLX, had to take a file to the backing plates, then found some made for that kind of boss and indexing.
Friends don't let friends drink and wrench.
1985 Raleigh Competition
Racing USA Series-Coleman made me do it.....
1987 Bridgestone Radac
- Aluminum (sadly, the frame is toast, RD hanger snapped off)
1988 Centurion Dave Scott Ironman Master
1989 Centurion Carbon-R
- Carbon Fiber