[1.7.10] Custom WorldType Spawn Location

I have created a custom world type,

however i cant find anywhere to set the spawn location

I have extended WorldType to set my own Chunk Provider and getSpawnFuzz()

my chunk provider implements IChunkProvider

neither of these classes seem to have anywhere to set the spawn location

currently i'm using EntityJoinWorldEvent to set position, as a temporary solution, but would like a better way as this moves the player every time they log in

Any suggestions