Here are my 2 options, which is best?

[nonovurbizniz]

the only advantage of the zc is that it's dohc... which isn't much of an advantage when

A. there are like NO parts for them (cams cam gears) I'm sure you could find lots of stuff that'll fit but that's a pain.
B. it's non-vtec.. Right?
C. it doesn't rev as high or have as much power as the built a6 would...

My recomendation would be to sell the zc motor (cuz it's mad jdm yo and will go for a good price)...
Build the D16bottom end up and put a y8 or z6 head and whatnot on... or just sell both and buy a y8/z6...

then build that up with rods pistons valvetrain etc...

it'll get you the most power and leave you with the least extra worthless bits laying around.

cam timing benifits of dohc are great and all but not worth loosing so many other benifits of the other d series motors.