Well, as some of you who chimed into my first thread know, I am looking for a new bike. I have been looking for a Nighthawk, but I recently stumble across a 1980 CB750 Custom with under 20,000 miles. I was wondering if anyone had experience or knowledge to share, or could comment on this bike compared to a Nighthawk. It doesn't seem like the internet knows nearly as much about the CB750 Custom as it does about the Nighthawk, although I seem to gather that the CB750 is the big brother to the Nighthawk...
In the mid to late '70s sales of the original SOHC CB750 were dropping off due to the availability of faster and more technologically modern bikes. Honda released the DOHC CB750 in 1979 to try and capture back some of that market. The DOHC CB750 was available in a few flavors from '79 until '83 - the "Custom" - CB750C - was the cruiser:

the "Supersport" - CB750F - was the sportbike:

and the "Nighthawk" - CB750SC was some kind of sports cruiser or hybrid of the two:

They shared the same basic engine and components (no big brother, basically an identical bike with a fancy paintjob and some chrome decals). They're heavy bikes, pushing 550+ lbs. wet.
The DOHC CB750 Custom and Supersport were superseded in '83 with the introduction of the Shadow and Interceptor, and the heavy, slow Nighthawk was replaced in '84 with the Nighthawk 700s/750s.
From what I hear, they're fine bikes, just don't expect anything extraordinary. You can find a forum for the Custom
here.