Silvertop zetec is probably the most straightforward non cvh swap. As stated you will need fuel injection fuel lines, tank and pump (you can use EFI or MFI) in addition you will need a modified engine mount from a CVH lump as one of the lugs doesn't line up on the back. A 1.6/1.8 lump is the easiest as it essentially drops straight in. To fit a 2.0 you will need a replacement sump, oil pickup, waterpump, flywheel and clutch to fit.

As Twins has suggested the RS1800 engine is the best of both for 130bhp. Worth speaking to both slammedorion (who runs a Zetec Turbo and built 'Pov' and orion zetec carl (do a search for zetec conversion) who are both Orion Zetec junkies and have really helped me with mine...