Are you looking at ECON CLB speed, or max angle?
According to the books (can't remember which one) max rate comes from max angle plus 25, and max angle comes from ref30+100. So for a heavy t/o where v2 (and therefore Vref30) is say 180kts, Vy=280, and Vx=305. There is an additive for weights above 317t, but since it is not quantified, I think it is fair to assume it is not large.
For a Max wt t/o I would expect the numbers to be something like..
Max Angle 280
Max Rate 310
Econ Clb 360 (CI=250)
Posting after a long haul, so treat info with caution