I think you will be OK with 130 - 150mm luff length.
The way to increase positive stagger is to increase the batten angle relative to the horizontal. You have designed an angle of 8 degrees, which is quite low. When you build camber into a sail, there is a need to increase the batten angle, to compensate for the extra length of the diagonal due to the extra cloth. I should use an angle of at least 10, maybe 11 degrees.
Have you considered using Arne's transitional panel, increasing the angle of the top sheeted batten so that the top triangles get smaller? I think you would find this worthwhile. Have a look through Arne's sailplans, and compare them with what you have drawn. Their proportions have now been well proven.
The lead should generally be around 9% of waterline length, for cambered sails, but this is a very inexact science.