For the front spring hanger of the rear spring we did the same, namely locating the bracket using the more rearward rivet hole on the frame and the most forward hole on the bracket.

The drawback is potentially having to use the stock leaf springs and shackles/hangers. However, the job can be all beneficial if you simply start out with the right parts to begin with.

How to build a custom spring-under leaf spring suspension and box the frame of a vintage 1948 Willys pickup at home.