Hi fella,they never made a 1.8 rs turbo fiesta fella but if you use the search function on here and select "go advanced" and search "zetec turbo" you'll find a ton of info.

You can use the 1.6 rs turbo head on your zetec block to make a "zvh" conversion but I think this is seen as a bit of a backwards step plus I don't believe it's too hard to put a blower straight on your engine.