Personaly I would bin the Sierra fusebox .........A hulking great lump, full of fuses & relays that you'll never need
Besides the engine loom.....The rest of the wiring is very basic & will prove to be quite simple if you break it into smaller individual circuits.
As said, if you are using the CVH engine as originally fitted to the car, try to keep the engine loom in one piece & don't bin any sensors.
Multi-core wire will be your best friend if you want to keep things nice & tidy