200 butts? :shocked: I can only fit about 10 or 12 in my Klose. :redface:
I'd say if you already know how to run a direct flow stickburner you're off to a good start. I don't have tuning plates - the size of my cooker doesn't really warrant that and I like temp zones anyway.
If you have temp zones - bigger butts in the hotter zones, smaller butts in the cooler zones. You might have a pop baffle between the horizontal and vertical chambers. With the baffle in, the temp difference between the 2 can be 50 degrees and with it out it can be 25 degrees or almost even if it's been running a long while. Take a look between the chambers and see if there's a plate (it should have holes drilled in it) that's held in place with a wingnut - that's the baffle. I would suspect there's one there.
Not sure what temps you like to cook at, but you may have to get temps too high in the horizontal chamber to be able to use the vertical for cooking, unless maybe you're cooking 275-300 in the main chamber and around 225-250 in the vertical, which is probably what I would do. I've never cooked on something that large though, so I can't say for sure.
Got pix of that cooker? I'd love to see it.