I think jano knows his stuff mate, why would you pick a 20 yr old 1600 that runs the same power at 8psi as a standard more modern 1800 makes in n'asp form? if you're going for big power with the cvh you're gona end up making expensive changes to the bottom end anyway, so do it with the bigger lump. if you run the bigger lump with the same boost you'll get more power per psi anyway, as more air and fuel are being forced in to an already bigger combustion chamber. It's nice to be nostalgic and have a cvh that can produce good power, but it's hardly the way forward.

Obviously with forced induction the restrictions of port and valve sizes are less significant as the air is not relying on the induction stroke of the piston to pull it in. So as the valve area is much larger than that of a cvh anyways, headwork on a zetec will only come into play once you've already got a nice power curve and when you want to improve off boost driving too, so you'll be spending money on your cvh head long before your zetec.