I fitted the OEM shocks from my CB750F2 to my commuter CB550F1 & it made quite a differance to the handling & extra ground clearance
At one time I fitted some CB900FZ shocks to my 550F1 but they were too long so went back to the 750F2 shocks
Hey yoshi what lenghts were the 750 & the 900 shocks ? I'm guessing you never did anything to the front end to compensate for the higher rear end ? I've got 14.5 inch Hagons for my 500, but still to get my act togeather and reassemble it after poweder coating. What issues were you getting with the 900 shocks ?
I'm not sure what the lengths of the CB900 or 750F2 shocks were, but it made it a very worthwhile modification as I was regularly running out of ground clearance with the standard shocks.
As for the front end of the modified 750F2 forks, I added some CBX550F2 air caps which, with about 5 psi pumped in, gave me a slightly better front ride height to compensate for the longer shocks.
With the CB900FZ fitted temporarily to the 550F1 it was far too high at the back, which didn't give me any tankslappers, but it did cause the bike to tip into corners much quicker as the CoG had been pushed forward quite a way. So I partially compensated by adding some useless imperial sockets above the fork springs, which kept the front end up & reduced the SAG measurement.
I'm sure that someone on here with a CB900FZ...like Steve...would be able to measure the length of the standard shocks. likewise, someone with a standard 750F2...like UKPete...may well be able to measure the shocks on his bike for you.