If you can fit a reaver with an apocalypse missile launcher you should be able to fit it on a 'wall hound' aswell. This is an interpretation of what I think a missile launcher would look like for a 'wall hound'.
Liek titans, so do I, that's why I'm here, to design more parts for warhammer titans. I also sometimes do knight parts. If you have any suggestions feel free to ask me in the messages thingy.