CGW has a heavy FPB spring you can install that will bump up the SA trigger a bit. I thought I heard he may have an x-tra heavy as well, not sure, but need to call because these are not listed parts.
If the #13 blue hammer spring is installed, you can go up to the gold #15 with the extended FP installed, but this will add a lot more to DA than SA
In SA operation the FPB spring gives a bit of a two stage effect so as the lifter block begins moving before the sear, you will feel it first before you get to the "wall".
Seems to work well on mine, putting the SA pull at just over 3# total.