I am looking for some information on what i believe use to be an OEM replacement head for the 2300's. I've seen a couple of pictures of one that was called an "M13" head. It is an oval port head with the heart shaped, closed combustion chamber. I'm looking to find out who and when it was manufactured and if it was ever sold on any production cars and if so, what year and model.  I've been told they came on turbo coupe mustangs and some rangers but i have searched and have for no evidence or information to support this. Any help or information about this head would be greatly appreciated. Thank you in advance.

I've heard mention that the carburetted early turbo Mustang was referred to as a 'high compression' turbo motor.  Maybe because it was slightly higher than the later turbo motors??? But the chamber shape I am unsure of. I've only ever dealt with 87/88 heads from Turbo motors.
 
Are you looking for this head with a specific purpose? While I doubt it is the case here, there are times people search for a turbo motor to run in a N/A application thinking it is "better." While they have forged pistons the compression is lower and the wrong way to go for N/A power.  I just site this as an example.
 
Have you asked over at Turboford, The Ranger Station or NATO? Other than a small handful here most don't delve too far beyond stock configurations . Also check Esslinger or Bopart. I am not familiar with them but they come up in performance head conversations.