Thanks for the replies. Yeah I was worried you would all say mount to the radiator. I'm reusing my 280mm radiator at the top, my 420 Doesnt fit at the front and would prefer to keep the 140 RGB case fans.
I've figured out that I can screw my rad mounts if I remove two velcro cable management ties from the other side and screw the mounts into those threaded holes. The pump I've managed to line up with some of the holes at the bottom of the case but it's quite near the psu. It seems okay thus far but I think the routes required for my tubes are too tight so may have to order new fittings and maybe hard tubes.