Affirmed. Early G15CS had a different spec, from 1966 on they all shared the same roadster parts. Early G15CS can be converted to the roadster spec easily.
I forgot to mention that the RE Interceptor Mk II employed the Matchless version of the Roadholder. Yet another reason to create a derivative of the Dommie Landsdowne kit!
The deviations are as follows:
NM16998 Bolt, top, fork inner tube (all N Dommie and =M= except 1964-66 G15CS)
030036 Tube, main (all =M= except 1964-66 G15CS). Length is 24.875"
NM18482 Tube, main (all N Dommie post 1960). Length is 21.8413"
NM20253 Damper tube/body (all N Dommie post 1960). Length is 7.625"
030037 Damper tube/body (all =M= except 1964-66 G15CS). Length is 10.75"
Apart from 1964-66 G15CS, other Roadholder fork internals are identical for N Dommie and =M= models from 1964 onwards.
Regards,
Knut