Dunno, but the easy way to see is to bind the string to the limb an inch or so down and test it...
It lets you try without chopping the bow.
I don't think you can gain much, maybe 5# or so, but it only works with perfect tiller and a bow that isn't going to end up overstressed by being shortened.
I often make a bow (English longbows) an inch too long on each limb just to give a bit of leeway.
Del