Having just replaced my Team primary on '17 ZR9000 I checked to see how much upshift a brand new Team clutch produces. On the stock ones, as you say, the shift-out ends when the bushing in the outer cover contacts the spider nut. At that point, there is about .050-.060" space between the movable face and the stationery face. With a new XS827 Timken belt (1.50" wide) it pushes the belt up out of clutch about 1/8-3/16".
I personally wouldn't want to see the clutch close up any more than it does stock for 2 reasons. 1, pushing the belt up out of clutch any more than stock to me is too much. And, 2, not knowing if the secondary can shift any more. IF secondary can't shift any more than a stock clutch does, then the whole shift-out will produce over-shift which will cause catastrophic heat and belt failures very quickly. Especially on a sled with 300HP. Could also cause jackshaft bearing failures.
Did you guys check to see if the secondary can accommodate the primary shifting more? And, did you see that the stock clutch already pushes belt up out of clutch?