My suggestion...

If your engine is in good health (not knocking or smoking like a Red Arrow) speak to this man Big Will and ask him about swapping your management over onto something like Omex.

A management swap with a bigger turbo (stage 3 T3 hybrid or similar) and a decent size cooler will see you with a reliable 210-230ish horses on the 1.6 CVH. The capacity has no bearing on how reliable the engine will be so don't keep thinking that you will end up with a more reliable engine than the CVH (a ZVH is the worst of both engines!).

Get a ported big valve head on it and you could be up to 250ish but may be restricted due to the compression ratio so probably a true 230bhp. At this point you would need a set of lower compression ratio pistons and a set of H section rods inside the engine and a bigger turbo to go further as you're borderline on the strength of the rods (same goes for a Zetec and ZVH engine although the compression ratio of the Zetec is against it a lot sooner).