The highest lvl drops in heroics is 463 so having all items over that makes it pretty, as long as you know the fights. MoP is a lot about movement fights, and that is very tough for a boxer. Gone are the days of parking the DPS in one spot and mashing keys. You gotta keep on your toes, stay out of the fire, click on bombs which are GTAoE, interact with objects etc etc. The good news is due to the ilvl you dont have to worry too much about damage and healing, so you can focus on positioning.

You might consider sticking to the timeless isle for the 496 gear first. Every bit helps.