Once the sear and hammer has been fit and the pull is crisp or smooth or however you may like it, the rest is the sear spring's left two leaves. The sear must have some tension, but can live with surprisingly little, the disconnector/trigger return, center leaf, can only go so low or will result in trigger bounce.
The sear hammer engagement will take about 12oz. by itself, so 1# on the sear and 1# on the center leaf will roughly get 2.75#. Simply increase for the 3.5#.
