Replying to myself. It wasn't too hard, just very fiddly with tricky to undo cable connectors for the lower bumper. I've got some rust on the impact bar though, am wondering if it's any point in replacing it for the rust? (The car has 190K kms on it, and will probably only be in service for three more year.)

Radiator support frame swap howto-mvimg_20190402_140101-jpg

Radiator support frame swap howto-mvimg_20190402_112042-jpg