Centaurus,
Boeing knows.
I am pretty sure that V2 min is based on VMCAx1.1 and Vr is based on 5% less than Vmca.
Of course VMCA was demonstrated/calculated by using full rate thrust,empty aircraft and most aft CG.,and BANK into good engine..so on line you normally get more margin as you normally use derate,have a rather centered CG and heavier.