Hmm, why can't you do the ZSU-23-4M then? I have little knowledge of the different ZSU-23-4 SPAAG models, but from what I can infer, the M seems to be better than the V1. Really minor differences only...
ZSU-23-4 was fielded from 1964, as a basic version.
ZSU-23-4V was fielded from 1968, it had the option of mixed optical/radio target tracking, to overcome jamming, and had increased gas turbine (V-6R) lifetime. (450hrs compared to 300hrs)
ZSU-23-4V1 was fielded from 1971, received new gas turbine (V-6R1), with 600hrs lifetime.
ZSU-23-4M was fielded from 1972, had a new canon (2A7M) with expanded lifetime (4500 shots compared to 3000 shots)
ZSU-23-4M2 was the "Afghan" variant without radar, and with NVG, and increased load (3000 compared to 2000).
ZSU-23-4M3 was fielded from 1979, with IFF.
As these advancements does not seems too major for the SIM, and I had the privilege to personally spend few hours in a V1, I plan to include this version...