ORIGINAL: Dubbya
Why not go with the 60-70lb limbs and back them out to the low 60's? That would give you room to work upward since you didn't mention shooting in the lower range of the 50-60lb limbs.
Well In the lower ranges of the higher poundages so im told you dont get such a great perfomrance as if you had a 50-60 maxed you'd see the peak of its performance not half of what its capable of.
Ryan.