Found the line. and everything is all hooked up. Just needed to get down at a different angle.
Bummed about the carbs, it was so much work to get them put on. How much of diagnosing, fixing am I able to do with them on the bike. I would imagine the overflows would not be difficult. I'm very green when it comes to carbs, that is why I had them sent out to be rebuild.
Don't get too discouraged. You've been making a lot of progress and if you keep going through the process of just finding the problem & fixing it you'll have a bike that's very rideable and worth $$'s in the end.
+1 to what Iron worker said. If you're needing a float height gauge, Joker machine sells a really nice one,
http://jokermachine.com/products/cafe-racer/honda-cb750-parts/cb750-carb-float-level-setting-gauge.html and vintageCB750 sells a cheaper one for about $11
http://www.vintagecb750.com/products/9/toolsTo me it sounds like one of the carb float needles isn't seating. Might just be a small piece of gunk from the tank or airbox. Here's what I'd recommend, try to isolate which carb(s) are the guilty culprit. Attach some clear tubes to the overflow outlets on the bottoms of the carb bowls. Run the other ends of the tubes back into a gas can. Turn the tap on, if one begins to leak, follow that tube back to it's respective carb. Turn off the fuel tap, remove the fuel bowl of the guilty carb. Get ready for some fuel to spill out!
Once the fuel bowl is off, check to see if the float is swinging freely on it's hinge. Should be nice and loose. If the float is nice and loose, go ahead and remove the float by pushing the float pin out of the way. The float needle should fall out, might not hurt to have a rag underneath to catch it. Once the float is out of the way, you should be able to unscrew the seat, I use a 10mm deep socket with a 1/4" drive, which is small enough to where it won't come close to damaging the float posts, like Iron worker pointed out.
Once you get the seat out, take a look inside at the seat, and at the needle. If you see a groove wore into the seat, or on the tip of the needle, I'd go ahead and replace them both (needle & seats are available separately and are not that expensive.). Chances are it's a bit of dirt that'll be in the seat, just blow it out with a little carb cleaner, reassemble, get the float & bowl back on (yes getting the needle to stay in place while trying to get the get the float pin back in, will take some patience). Once everything's back together go ahead and turn the fuel tap on and double check everything again. If the floats are set correctly and the needle & seats are clear, shouldn't have any overflow.
