Will 11 speed 55-42T Shimano Dura-Ace 9000 crankset will be compatible with an 8 speed 11-28T cassette and shifter?
Nominally no, an 11 speed speed crank will not work with an 8 speed drivetrain.

As the number of speeds (number of cassette sprockets) increased as new groupsets were released, the sprockets were narrowed and moved closer together. The outside width of the chain was also progressively narrowed so that they worked with the narrower sprocket spacing. This also meant that crank chainrings had to be moved closer together. An 8 speed front derailleur and chain will not shift at all well on a 11 speed crank.

Other things you should bear in mind if you are serious about a 55/42 crank. You may not have enough chainstay clearance for the bigger rings, and you will need to check that your front derailleur will move up enough - some braze-on clamps don't have enough adjustment.