Blacktop requires the sump modifying to clear the starter motor and offside drive shaft, the water pump sits closer to the chassis leg and you need to use a idle pulley to change the direction of the Aux belt so the pump turns the correct direction. The bottom hose to radiator also is more challenging to get a nice fit. Blacktop needs a notch cutting out of where the engine mount bolts to on the chassis leg to clear the timing belt tensioner. Blacktop usually needs a bracket making to drop the escort cvh alt bracket down so the water pump outlet and alternator clear each other.

Silvertop Sump no mods, CVH alternator and bracket bolt straight on with just the zetec pulley added to the CVH alternator, then run the aux belt in a simple triangle pattern. Off the shelf bottom hoses are available for a silvertop into a escort rs turbo.

Silvertop easier to fit, but Blacktop is probably gonna be easier to source.