did you get a sohc zc or a dual?
b16's are about 1100 for hte price, $600 for mount and wiring and shift linkage.
$4000 is a highly inflated price.
zc is a good start, the potential is higher with the b series that's why everyone pushes them so much more.
i would've said b series, the zc's are nice. good swap for a beginner.