i was under the impression that the GSR and ITR blocks were more or less identical and the biggest difference was in the head.

 

Lord no, the ITR blocks, rotating assembly, head are all hand assembled with hand ported passages and very precise/strict guidelines/tolerences. The GSR is like the B16A as it is a mass produced by machines with much less attention than the ITR. To take a C5 and built it's internals IMO you get away from what makes it a Type R which is bad *** because it highlights Honda's ability to build a engine in the late 90's.

 

The Type R blocks were the best B-series blocks Honda produced. But they're not worth the price tag imo. If you want a motor to turbo charge just get a B16 or GSR/B18C. If you want a mean NA motor look into more customized set ups, like a B20/vtec or H22. If you want a well built NA motor that you don't have to do anything to, get a B18C5 and don't touch it.