A B777-300 at 299.7 Tonnes has a V2 (Flaps 5°) of 192 Knots. Under the most limiting conditions it must achieve a climb gradient (Gross) of 2.4%, and 2.4% of 192 Knots in the Standard Atmosphere is a Rate of Climb of 467 Feet per Minute.
That's the minimum performance.
Regards,
Old Smokey