Lu,
The RPM on the Zsu - Is that per gun, or all 4? if it's per gun, then thats 4800 rpm, or a blizzard of lead.
The Canadians used an improvised Sherman in the latter days of WW2, mounting 4x .50 cal Brownings, as an ANTI-INFANTRY device.
It worked bloody well too, from all reports. Does the Zoo have a ground to ground capability?