Commander, we calculate Vref straight from flap setting and gross weight.
Max landing weight on the 767-300 is 145,150kgs, a typical mid landing weight would be around 125,000 - 130,000kgs, at which point the Vref30 (Vref at normal landing flap, flap 30) will be around 135kts.
To give you an idea Commander, at 100,000kgs Vref30 is 119kts, at 145,000kgs its 145kts.