Very nice set-up. Once you get your Oly barbell adjust where you want it in rack, add weight and it will hold you down when doing pulldowns. If not totally comfortable wrap a towel to get it to your liking.
Lat pulldowns with some weight finally. Very smooth and can actually do them inside the rack too if I move the pulleys to the middle and back mounts. Right now they are in the front and middle locations. It will allow for a more vertical pull.