yeah, have you looked at the price for parts for a worthless B-series? They are outrageous. The D weighs less, has roughly the same torque and the parts prices are alot cheaper. Ditch the B-series and go with a D. Out of the options you have, I'd go with the JDM D15B OR (and i know its not one of your choices) D16A6...vtec is over-rated.

D15B for its nice rod:stroke ratio, same head as the Z6, same block as the Z1 and power is easily made just like its .1L counterparts.

D16A6 for its better main bearing cap(has a steel cap instead of a slightly weaker all aluminum piece like the Z6/Zc vtec), same block as the ZC, same head as the Zc non-vtec and 88-91 Si/ex/dx ; 92-95 Dx/Lx, nice torque and hp gains when cammed. Oh yeah, ALOT easier and cheaper to work on.

Parts for the D-series are easier to come by because of its high compatibility with almost all 1.5's and 1.6's.

I have about $1200 in my A6 motor build and will be spanking B's, H's and K's with it for alot less then it would cost just to swap one of those in my car.