BTW, if the length is close (I kind of doubt it is), you would be well off to fit the CBR front end to your CB. Those forks are way better than the stock CB damping rod forks, even with emulators added.
With all due respect to Retro Rocket, I disagree about progressive springs - it seems that most suspension gurus prefer straight-rate springs. With progressives, your suspension is just about guaranteed to be over-damped through the start of the travel, and under-damped at the end.