If you want to keep it a CVH, it'll be big money to get decent power, I'd personally build a Zetec Turbo for your power you want.
Friend of mine just built one, I'd say its 250bhp @ 11psi (base map) and its fucking RAPID! It is in a Fiesta though! But it was a damn site cheaper than a 300bhp CVH would be..
Gearbox (CTS Stage 2 or MTX 6speed) , suspension ( Coilovers or a decent shock, TCA's, Polybushed), brakes (ST170 Conversion,Cossie 4 Pots or something like AP's), will also add up the cost too!
A cossie T3 will push an engine to 300, But I'd personally go for a GT28rs. A FMIC is always a good idea too.
Keep us updated on what you do
When you say carbs, what cars you had before?