Okay here is me being knowledgable. f23a1 is vtec, f23a4 is ulev vtec and F23a5 is non vtec. The h22 IM will not fit the f23a1 which is the vtec head. The f23a4 is the ulev vtec which means that it is ultra low emissions, and from my understanding, the exhaust manifold is different, along with the upstream o2 sensor in order to comply whith the ulev standards (I think the Ulev sensor is a wideband sensor). So with that being said, no, the h22 IM will not fit on the f23a4.
But since I'm a very rude person, why the **** would Honda redesign the head of the f23a4 and make such drastic changes between that of the f23a1 and the f23a4? It's common sense that they wouldn't change the bolt pattern and design of an engine head to obtain lower emissions .. but honestly, I'm not rude .. It's just common sense man.