Version 4.8 of engine actually uses Oculus SDK 0.5.0, here are relevant git commits:
/EpicGames/UnrealEngine/commit/010b67402085fbef8a0e77c7e37834b7366421de
/EpicGames/UnrealEngine/commit/7e8d7ed115ff3c63701cda1fcd0f3d15eaa7263a
/EpicGames/UnrealEngine/commit/7b6221fc079ff291edc0c483da95373bd06ec63b