Hi Stratos,
this should do the trick,
activate this MOD with JSMGE
It does not replace the default ZSU-23, it is an addition.
I've changed the caliber with 7.62 rounds as far as we do not have the real ZPU-2 in DCS. (i know it possible to create custom caliber, but don't know how to)
You can play with calibers at line 55 of ZPU-2.lua
Hope this helps,
Cheers, Franck