I doubt very much that you'll see any fuel moving, especially since the bike hasn't started yet. You can check to see that the bowls are at least getting gas just by removing the bowl drain screws and confirming that gas runs out. Actually, I suppose you could look at your fuel lines to see that gas is moving, assuming that your lines are clear. You should get a decent flow with the drain screw out, but don't expect to see that same flow just from starting the bike.
In my opinion, you picked a pretty hard bike to work on as a first bike. I think the older 750s were much easier overall... again, my opinion. If you think you have a vacuum issue such as sucking air, you can check by spraying starting fluid around the connections at the insulators (between the carbs and head) and between the airbox and carbs. You can also use a propane torch like for soldering copper water lines (just turn it on and aim it at the possible source of a leak.don't light it! lol) If rpms increase, you have a leak. Problem is, the bike needs to be running and you're not there yet.
You've had the carbs off... how did the insulators look? Hard as rock? Any cracks? Are you confident that the clamps pulled them tight around the carbs?
When you twist the throttle can you see any squirt of gas in the carburetors? You should look closely into the throat of the carbs and see a small nozzle sticking up at the bottom... you should see a squirt of gas when you twist the throttle or your nozzle(s) might be clogged or the accelerator pump isn't doing its job.
I assume you've checked the plugs to be sure they're firing. Even though you've replaced them, if you've been trying to start it for quite awhile you might want to get another set of new ones. You might also get by with just removing and cleaning them with a wire brush or compressed air, or both, but don't overlook the fact that you could have fouled plugs.
I just re-read your initial post and see that you said you removed the "air cleaners"... are you saying that the bike has pods instead of the original airbox?
Have you thoroughly cleaned the carbs, or just removed the bowls maybe and sprayed carb cleaner in them? Here's a link to a carb cleaning manual available from another forum... a very good source of information. Pay particular attention to cleaning of the jets and carb body orifices. I actually won't recommend that you take the carbs completely apart at this point, but you can remove the jets and do the majority of cleaning with the carbs still left on the mounting bracket. This is a good read and you might get some feel for how well you cleaned your carbs. I wasn't very good at... I think it took me 3 times (or was it 6) to get my 900 running well, and each time after cleaning I'd swear I did a good job. Here's the link:
http://www.cb750c.com/publicdocs/SeanG/Honda_Carb_Manual_revF.pdf
From that same forum is a checklist for new owners of DOHC bikes. Maybe a bit of overkill, but another good source of information. Here's that link:
http://www.cb750c.com/modules.php?name=Forums&file=viewtopic&p=68364
I'm sure you'll find others who know way more than I do about these bikes, and my only experience with the 80's CB models was with a couple of 900's. Someone will surely chime in and offer some helpful suggestions. For now I've hopefully give you something to work with for starters... yeah, pun intended.