Jubilee fork oil how much.

According to an original  Twin cylinder manual from the sixties it says on bottom of page 51:

Refill with 70cc of S.A.E 30 oil. That´s per each fork leg.

The later Navigator Roadholder fork takes 142 cc per leg.

http://www.eurooldtimers.com/eng/manual/94-norton-twin-cylinder-re-build-manual.html