Is it be possible to include op codes (321, 321+ ...) from EE to the original BG?
No, i already wrote about new opcodes for old engine - too late for old engine, most modders moved to EE and never go back
Wrong.
Only new players have probably never played oBG games. But I can assure you that if SHS Staff would announce we stop updating pre-EE mods, we would fire a revolution!
The success met by your mod and Tobex revival should convince you of the contrary. Moreover, you can't imagine how my inbox is full of requests sent by old players - always active because you can't quit the BG saga - asking for retro-compatibility updates.
Instead of spending weeks to find more or less accurate workarounds to make new mods compatible with oBG2 (when it is possible), being able to use many new opcodes in old engine would save our time.
But I don't have enough technical knowledge to state if it is feasible or not, and not too tedious to achieve.