Decide how many threads you want, here is my reply from your other:

On the front of the head above the exhaust manifold you will see code stamped onto it, look for PR3.

This narrows it down to B16A or B18C5.

ITR head is port & polished and the valvetrain is different.

ITR's come with dual intake/exhaust springs, B16A's have single exhaust valve springs.