Yes, the reference VREF30+80 is the same, however as the 763 is heavier, you will see a few knots higher speeds, upto about 260 kts at gross weight on the 763.
But wait there's more. Vref30 will also vary with engine type - for the same weight, RB211 and CF6 powered 767-300s will have Vref30 speeds differring by a few knots.