The Type R head is a B16 Head that is lightly ported, with a better valvetrain and more agressive cams to make use of the extra flow, and in 96-97 Specs, hand built and ported. By 98, they had ultra-precise automated systems doing the porting which were miles better than the previous spec. Still hand assembled though.
If you want to do porting work later, go for a B16 head and save some cash. The B18C5 heads are great the way they are, but are almost too far gone to get agressive with porting options. The GSR head is honestly not worth the money because as much as anyone tells you, the GSR head does NOT flow that much better than a B16A head (if at all) to justify the usual price diffrence. They are meant to flow the same HP, and the only reason the GSR is a faster engine is because of 1.8L>1.6L.
My two cents, go for a first gen B16A head for dirt-ass cheap, get a basic valve and porting job, have it re-decked, and try and find some used Skunk2 cams, and if you can fit it in there, an ITR or Skunk2 valvetrain + Intake manifold. I'll bet you you could pull that build off for the same price as a Type R head any day of the week. And it'll be 100303488x better than a Type R head.