The client really should be the one generating this stuff, sending actual assets over the network isn't the best use of bandwidth (of course, maybe you have something different in mind, but from what you said it sounds like an overly complicated method to do things)
The thing is,the terrain must be persistent and stay on the server and during the game players can affect and change it from time to time,but it's not really a problem - each zone has a tileset and each tileset has 8 different terrain types,so that's 0-7(3 bits for the tile type) and same for the tileset - 8 tileset types.
The point is I have to get the client to turn this received info into a blendmap pixel by pixel when receiving the terrain chunk data.