yes, that should be fine. you can get as close as a foot with a 600 assuming it is air cooled, but just because its not hot doesn't mean that you can't burn the plants. The lights emit a lot of lumens, and while it is nice to give your plant ample light, you can give them too much and cause light burn. If you notice a weird yellowing / an odd patch of yellow on the top leaves of your plants but your plant and lower leaves are healthy, it is most likely light burn