Hi!
They will fit, I know because I have made the transplantation myself and all the welding. Since you have a 1966 with a low ch.nr. I suspect that you will not get the exact design of the reinforcement, but that is maybe a minor problem if you do not want 100% originality?
1966 and 1965 2000cs are becoming very rare nowadays. The earliest versions used stainless steel instead of aluminum in almost all the ornaments, which is more or less impossible to find replacement parts of today, however, it will make the car heavy as a tank, and given the power of at best 120PS, you will have a very undermotorised car.
Best regards,
/Johan