How much wear is there on the drivetrain, is what you should try to find out. 5 year old Dura Ace is still a 5 year old group set. If the components are worn, they are expensive to replace. Even the cassette lists for close to $300. Nothing on a bike lasts forever, and a hard-ridden bike may have hard-ridden, and/or poorly maintained, components.
Has the bike been crashed? Any visible signs of damage to the frame?
In the abstract, Kyserium wheels are good, but again---how hard have they been ridden?
Also, 63 cm is a HUGE frame. I'm 6' 2" tall and I ride a 60 cm. A 63 cm frame would be for someone 6'5" tall, probably.
BTW, the FSA Gossamer crank is nothing special, and a far cry from Dura Ace. You really need to find out exactly what components are Dura Ace, and what are less than Dura Ace.
To give you some ballpark estimate on worth, a 2013 Super Six with a SRAM Rival group and Fulcrum 7 wheels lists for $2750 and can probably be had for around $2500. Fine frame, decent group, and you get the benefit of a new bike warranty (lifetime on the frame). Buying used, you get **** nothing for a warranty.