I would leave the downhaul as is : that is that the downhaul pulls on the boom which in turn is connected to the sail and pulls it down with it. You might want to replace the cleat by a cam cleat or jam cleat.
I would also make the outhaul like it is done on the A-cats and currently also on the Tigers and FX-ones. A loop of webbeing or big Stainless steel ring running over the boom and which has the top attached to the sail and the bottom to the mainsheet. The outhaul of the old hobie sail can then be reused to position the ring and set the curve of the foot.
For pictures see the Taipan 4.9 setup on :
http://www.geocities.com/f16hpclass/ahpc_taipan_49_how_to_rig.htmlfourth picture from the bottom of the page
WOuter