i've had my 1.8zvh for just over a year and a half, 11 months sat in garage lol!
from my few months driving it, it's all good.
bit of pissing around with oil returns and mounts, then you're off, more torque and bhp off less boost.
basically i had 15 psi of boost and the clutch slipped a little, when i fitted a zvh on a ported head with bigger valves and standard cam, i had to turn the boost down to 10.5psi to reduce clutch slip and it did it a bit then too.
so a comparisson of power there for you.
i'm now on efi and using a 4wd cossie turbo as this is the biggest before a t34 or gt series turbos on a 0.48 housing, basically a stage3t3 without the 360 bearing so should be fine for decent power.
also blocks are everywhere and so are cheap and not old abused units like rs blocks which are getting on now with fatigue etc.
all these people chasing big power on a 1600, sounds daft to me, up the displacement and you're so much better of from the start, cossies are 2.0 to start with, as are focus rs(mk1).
i've heard stories of 2.1 zvh's making 300bhp on 12-13psi in some cases