Here's some shipping info on the Trent XWB engine (from VRR, the pallet manufacturer):
The engine stand that the Trent 1000 engine is shipped on is based on a 196x125 inch pallet. This is a non-standard size in the aviation cargo industry, but it can still be loaded onto some types of airplane. In this case, it’s often a B747 or B777 freighter aircraft. The engine, including the transport frame, just fits through the door of these planes, leaving us with only 1 inch of headroom to construct a solid and rigid pallet.
fwiw The A350 inlet cowl only has 3 inches clearance when going through a B744F nose door.