Well, I got two CB750's. A '74 CB750K-4 and a DOHC '81 CB750C:
I know, the CB750 Custom looks like an old mans bike. Backrest....windshield....poor mans highway pegs....cargo rack with removable lock box...etc. But I like it. The back rest slides all the way back to the lock box so me and my bride can take those long leisurely trips in comfort. I installed a 38 tooth rear sprocket to get the revs to calm down. Successfully replaced the stock air box with pods, even though the experts will say it can't be done. No more all night cursing sessions when I want to remove the carbs.
Both of these beauties have a PAMCO ignition system, of course. The CB750K has been around for a couple of years. The CB750 Custom is a work in progress. It works just fine, but not ready for prime time.
The pipes on the CB750C are Mac 4 to 2, but with my own custom baffles as the sound of the stock Macs is awful, IMHO. Not meaning to say bad things about Mac pipes, because the pipes on the CB750K are also Mac 4 to 2 and they look and sound great! I think it may be because the SOHC was around longer and Mac was able to develop the mufflers to a higher degree.
The longer wheelbase, bigger tires and more weight, along with the "pump up" forks really make the CB750C my favorite. The ride is incredible. I always feel stable and under control, especially with those dual disk front brakes.
When I'm not riding the CB750C, I take the CB750K-4 for a spin, just to feel young again, and, boy, talk about revitalization! The CB750K-4 will pull your arms off with it's torque! Great bike. Handles well, although a little choppy compared to the CB750C. The original Crotch Rocket.