well let's takes this question in several steps. first off, let's take the dual point and not multi point answer.

dual point - 2 injectors (d15b2)
multi point - more that 2 injectors(d1616)

now that we got that out of the way lets take the next part.

head - the d15b2, d16a6 and the d15b7 all are made from the same head casting. the difference is the cams and springs(well get back to this).

sohc cams - the d16a6 is the better cam but you can put this cam in to the d15b7 head w/a d16y7 or d16y8 cam gear(they're the same cam gear) to make it work. the y7/8 cam gear would make TDC w/o any headache, just put it tdc and go. now i want to make a extra footnote about the ZC non vtec cam. a d16a6 cam and a zc cam are the same cams the only differece is that a zc can is retard 5*(4.75* to be exact) so it gives an aggressive profile. you can have the same aggressive profile w/an adjustable cam gear to the d16a6. and w/a y7/8 cam gear on a zc cam it will be tdc too in a d15b7.

springs - the first question should be what year is you d15b7 head? why? well in the later 94 honda ran out of d15b7 head spring so the went on and used d16a6 springs. hence the d16a6 spring are a bit stronger than the d15b7. and they are good up to 8k reving for the ricer.

so in final why slap on a d16a6 head when all you have to do, is just slap in the a6 cam w/a y7/8 cam gear to have the same head?

and finally the magic question if the d15b2, d16a6 and the d15b7 are the same head why do they have different hp. simple the ecu tuning w/cam profile, and several other things. but in a N/A engine alot of the hp is made from the head and tuning.