disco v8 on strombergs

Hi folks, looking for advise on the carb setting on my disco. She's a 3.5 v8, manual & running on stromberg cd 175 carbs with k&n cone air filters. It runs & starts ok apart from under full load, it seems to be running a bit weak. I know this is due to the k&n filters alowing more air in than the standard filter set up. Anyone got this set up or had any dealings with in the past? will adjusting the needle hight/mixture be good enough or will i need different needles to compensate for the k&n's???? Any help would be great... Cheers.