Frank, they were about a few years before that mate.
In 1967, Colin built a frame for the factory 350 Honda four GP road racer complete with the forks and his own twin front disc set up for Mike Hailwood to race in none GP events.
Although Honda would not let him use the bike in GPs, Mike did tell them how good the set up was and it makes one wonder if this was the reason that the CR750 race bike of the following year were fitted with the same.
Thanks for connecting me to this post Mr Murphy.
Sam.