with regards to your conversion, you'll need to:

make one side engine mount (cvh mount will fit other side)

fabricate or buy (£200!!!) a water rail to relocate the thermostat OR modify the bulkhead to allow clearance for the original item.

use cvh sump and pickup pipe if using a silvertop, on a blacktop, they need modifying a little to fit correctly.

you can use the sierra flywheel and clutch, but will need an alternative trigger wheel for the management system (the cvh front pulley can be used if you space the other pulleys out a little)

you will need an efi type fuel tank, either cosworth style with external pump, or late efi style with an internal pump.

wiring is easy really, you should only have around 5 wires to connect the engine into the car. if using a late mondeo loom, you'll need to keep the key strapped to the immobiliser.

as you're using a standard engine, both early and late will be fine, but early is probably the easiest to fit.