Scooby, this is an old school nacra 5.7 with dacron sails. Lots of downhaul won't curve the heavy ally mast like it does on our fancy tapered carbon masts. More downhaul is only going to stretch the old sail more and more, with minimum effect on the draft.

To flatten the sail on those keep the diamond tension low, rotate the mast and it will bend on the smaller axis when you pull the main *tight*. 3:1 downhaul purchase is sufficient. Now if the main is changed to something more solid and less stretchy you try to can bend the mast on its major axis with a downhaul, but the main needs to be reinforced first, the spreaders need to be swept back a bit (I don't think they are tunable on a 5.7), and the diamond tension needs to be tighter.

To answer the original question, assuming that the problem is due to the new flat jib and the baggy main narrowing the slot, you should move your jib sheet pulley back: it will tension the foot of the jib more, and the leech less, opening the slot between the main and jib.