if you have an a14 your intake/exhaust is likely oval port, so changing to an a15 head is likely more feasible for you, as it too uses oval ports. the a12 head will have round ports. someone else on this site will be able to answer in muuch more detail in respect to the rest of the bits inside the head, if changing from a14 head to a15 head. the answer may lie in the Tech Wiki too..