12ST head

[arturbrandao23]

Hi all. Greentings from portugal.
I have an idea of building an motor for my corsa.
I have here at home an 14NV block and i saw a thread with some ideas of building the motor with the 12ST head,
I have one here but i'm not sure if it's from an 12ST or from a 12NV, both carbureted, motor. Can anyone tell me the diference between these two heads?
I'm sorry for my english, and thank you all for the replys.

[millworm]

The head from a 12nv will have square ports in it, the st head will have more rounded ones