the b16 head is also the head used on the type r.. the type r has different valve train, im, tb, cams and a mild port n polish job.
the gsr head is a b18 head.. not the b16 like on the others.. the only 2 downsides are.. 1) it had a different intake manifold (IM) bolt pattern, so the b16 one wont bolt and the IM has secondary butterflys, so you need the ECU to run them, or you will lose power.
IMO, i would get the b16, its typically cheaper (around 450 complete) and you add type r IM and other IM's without the queston (will it fit?).
I would get the b16.. hope that helps.. look at these, they might have one forsale.