I would use Weber (Cosworth) as a decent ECU which will be able to control your engine no problem could cost as little as £60 on Ebay.

The money you could get by selling your MFi Items like Chipped ECU, Mixbox etc etc.. would pay for most of the Weber EFi management parts.

Once fitted to an engine the limits are endless, which is where a well built engine comes into account.

Your talking about dropping a ZVH into your bay. Why not just use the Zetec head which will probly cost less than machining your CVH head and Zetec block for a ZVH. Its pointless restricting a decent Zetec block with a CVH head.

How much is the best CVH head you could buy gonna cost??? £800?900?

Compare with a STD Zetec head which will probly flow around the same £100