I owned a 1987 GSXR1100. It was mostly in original condition with the exception of an aftermarket pipe, 36 Mikuni flatslides and a set of light weight Kosman wheels. I've had a chance to ride a few CB900F's and I will say the Zuk outperformed the Honda, hands down. It even handled better in my opinion. I loved that old bike. Unfortunately it got stolen one year while I was in Daytona for bike week. Oddly, I had my bike chained to a pole in the parking garage with a disc brake lock. There were newer model bike parked all around it but the low lifes pushed those bikes out of the way to get mine. What a let down for me. I only had liability insurance on the bike due to its age so I took a total lose. Hindsight says I should have had full coverage.
So, my opinion is to go for the GSXR