Pics first now that it's 'home'.

EDIT: This completes our introduction. Copying this post to 1500 Tech. All further posts on this project will be there. Carb internals undetermined as yet, but looking flaky. Opened float bowl drain screws produced no fuel. Hmmm; might be good, might be bad. PO doesn't remember if he drained them 14 yrs. ago.
Introduced fresh fuel from our aux tank to check for any leaks in the 'O' rings of the fuel rails. Fuel immediately leaked from a loose hose at the first 3-way joint just downstream from the petcock that splits feed to each side. We probably dislodged it when we pulled the tank. Got that back on courtesy long right-angle needle nose pliers.
Next feeding revealed fuel running out of one of two hoses that drain next to each other onto the top of the motor between carbs 5 & 6. These two hoses appear to originate from the uppermost 3-way joints between 3/5 and 4/6. It's the 3/5 joint that is producing the fuel.
Our gut sez stuck float(s) and / or float valve(s). We tapped on all the float bowls with a brass drift without effect. When we opened the drain screws fresh fuel flowed, but slower than we would have expected.
It's clear we don't understand these carbs very well, as we would expect the uppermost 3-way joint to be associated with air somehow. Seems too high on the carb bodies to have fuel in them, but the presence of a drain indicates the possibility was anticipated. Perusing the hose layout in the FSM and on Partzilla trying to identify the function of the rails the uppermost 3-way joints (or even locating them in the drawings) has been frustrating 'cause we don't know carb rack & hose nomenclature well at all.
Insight anyone, please?
At any rate, it's certain the rack has to come out for internal cleaning. We have decades of experience with Z1 Mikuni slide throttle VM carbs, and a little experience with '90's Keihin CB750 CV carbs. We have a very good ultrasonic tank & our choice of two varnish-busting solvents to run in it. Main thing we have to do first is, rearrange our carb bench to accommodate a six carb rack instead of the usual four, and that is both wider & deeper than we're currently set up for.
We're gonna be busy with other stuff, so the next update will be at least two weeks out.
Thanks for the assistance everyone.
Good Ridin'
slmjim & Z1BEBE