Is it possible to flash CM for Samsung S3 I9300 on different version?
Simply no.

i939 is a China Telecom variant, and has a CDMA baseband, along with other minor differences (there's a variant of i939 itself that even differs in dimensions). Unless the build was specifically marked as compatible with multiple variants (e.g.  S3 Qualcomm versions, aka d2lte, share a single CM build), the build will be limited to that model only. It's even more obvious considering i9300 is a GSM-only device.