Not sure what you mean by 100 percent accuracy and of course, you probably already know this but 3.5 Instruct Turbo plays chess at about 1800 ELO fulfilling your constraints (and has about 5 illegal moves (potentially less) in 8205) https://github.com/adamkarvonen/chess_gpt_eval
Not sure what you mean by 100 percent accuracy and of course, you probably already know this but 3.5 Instruct Turbo plays chess at about 1800 ELO fulfilling your constraints (and has about 5 illegal moves (potentially less) in 8205) https://github.com/adamkarvonen/chess_gpt_eval