I have a '78 CB750A. It starts fine with the choke out, but as soon as it's pushed down the bike dies. I have good compression and spark. It sounds like it runs out of gas when the choke is pushed in. No clogs in the tank or lines. The only issue I have had with the bike in last two years is last year it fouled the plugs a few times.
The fact that is wouldn't run without the choke in that it in running lean.
Have you got fresh gas in the tank? If so, I would add a good dose of Sea Foam to the tank. Maybe a couple tanks.
Run it that way for a while even if you have to use the choke part-way.
If that doesn't help you will have to remove and clean the carbs and that is somewhat of a pain.
I would give it a real good chance with the Sea Foam.
I doubt running seafoam will help in this case. if the bike won't idle, the slow jets are plugged. Since there is no fuel getting thru the slow jets, any seafoam won't have a chance to unplug it. The idle jet is really small, you'll need a high E string from a guitar to unplug the jet.
I just got done with this. Seafoam should help with everything else.
if your bike has been sitting for more than a month without fuel stabilizer, I would drain the bowls and tank and put fresh gas in *BEFORE* starting the bike.