FJ5 Faker, I would say between February 15 to 30th of February 1970. I did compare your VIN with the ones in the Registry.
Jaybe, there must be an error in the one you posted (BS23H0B...) is a 1970 Cuda. The build date 11-70 is for a 1971 model.
Let me know your car's VIN, I can check for you. PM me, if you do not want to post your VIN in full or xx the last two digits.