When I did my SOA awhile ago, I went with Bilstein 5100, if I remember that number correctly, series.
My understanding on this for new shocks, after any type of lift, is to take three measurements.
1) static height.
2) compressed
3) droop
I have ordered several sets of shocks for SOA conversions. And came up with several different numbers. I think it was due to variations of the leaf springs. Once you get those measurements, then you can call up the fellas up at IH Parts America and place your order