It depends on what you have to start with?

A Zetec block is lighter than a CVH
A Zetec block has a more reliable and effective oil system
A CVH fits !!!

I have a fully built up focus RS engine sitting in the workshop needing a home!

Having had a big power CVH 1.9, 2.0 ZVH and a big power Zetec my opinion is Full Zetec for 300bhp.

S.