got this all done & did some initial testing today
6x 8mm holes per damper rod (ie 4x existing, 2x new)
20w oil
1.5 turns on the emulator preload
.80 linear springs
typically enough I found my shiny new crush washers about an hour after refitting everything .. grrr
haven't had much chance to test, just a quick scoot round some local roads, but seems to be very nice, much increased low-speed compresion damping & nicely controlled rebound. looking forward to giving it a good test at silverstone on tues