Kasuga retro fit

I finally got the Kasuga V-2 into the shop. Need to replace the
resolvers with encoders,or replace he Western Servos [lotta work]
anyone have some slick ideas on getting some encoders mounted?
should I try to tap and extend the motor shafts?
Motors are pretty good size,90v9a,should be good with Gecko 320-340
at 80v.

thanks
carl