Interesting data, thanks for sharing. The Federal load you show clocked faster than a Speer 125 gr GD +P load I tried, they averaged 867 FPS through my 637. The same load averaged slightly faster in a model 36 at 876 FPS. I also had chronographed some BB+P 125 grain Gold Dots in the 637. That load averaged 1014 FPS. I don't have any left but seem to remember they were both loaded with the 6-petal configuration GD projectile.
I recently managed to pick up some Speer 135 +P Gold Gots from SG ammo. Unfortunately as winter in Wisconsin is determined to stick around as long as possible this year, I have not yet had a chance to run any over my chrono.
Going back to the OPs question, I have seen a number of videos on You Tube that show the BB 158 LSWC HP tested in gelatin, both standard and +P versions. If you have not looked yet you may want to do a quick search.