Still be interesting to know what loom you've bought? Fiesta turbo - OFAC or OFAB? Escort Mk4 EFI? Depending what you've got, there may be some wires that need cutting.

The only other issues are the breathing system, blocking some oil returns, and using the correct head bolts. You can use Duratec V6 head bolts - but you MUST use the CVH head bolt washers AS WELL AS the washers that come on the Duratec bolts - otherwise the head will not seal properly. I had a leak but luckily I found it just by turning over the engine to fill the turbo feed with oil. With 2 sets of washers it appears to have sealed - touch wood.