Most people go with the Trick Flow Stage 1 cam and TFS spring kit for those motors.
You'll need the fox timing cover/bolts, timing pointer, water pump, egr spacer/bolts, oil pan, oil filter bung, dipstick, pulleys, hamonic balancer, coolant pipe on intake, valve covers, distributor, and front bracketry to convert an Explorer motor to Mustang. You can transfer all of that from your old fox engine, that's what I did.