if they are rooted go for it i would start with the weaker bulb though. it also depends on what kind of lights the mother plant was on and if they are already used to it
400w on ROOTED clones should be fine. If you're worried start with the light 5 or six feet away and lower it every day until you're either too close due to heat, or your plants are getting what you think is a little too much light and move it up.