I only ran the K&N with the stock carb, before the HRD build. I started with a Lectron 44 and a 4x8 Uni dual layer foam filter.
600 main was about ideal running China Wall last winter. 620 would not pull the hill in 4th, but 600 would. This was then F&L 111 w/Amsoil Dominator 40:1.