First off...really nice tank, can't wait to see your progress...
As to tank size, you're almost right... Everyone usually quotes tank size by 'outside' measurements, so IMO, you should be proud to list the tank as 560g
That said, it is important to have an idea of the true capacity of your tank and total system... as to the inside measurements of 118.5" long 34.5" deep and 28.5" high, making it 504.36g, I'd think that the inside water level would be at least 1" from the top, making it ~27.5h, so ~486g, less any space in the overflows, and displacement by sand and rocks...
but who cares...you got a 10ft 560g tank...Congrats!