It all depends really on your plans and fitness for the bike with gears and ratios?
My cardio and overall fitness is pretty good (Tough Mudder last month, sub 50min 10k, etc). We did the Bealach Na Ba loop in April, and were thwarted by blizzard conditions and 2 inches of snow 500 yards short of the top. We will be back!
As for cycling specific fitness, I need some more miles on my legs right now, but that will come with the arrival of a new bike
Dura ace is the top level with ultegra behind it but REALLY a Colnago would be better suited to Campag?
I noticed the older Colnago is fitted with Campag kit, and there is a lot of Campagnolo spare parts.
The reason I've suggested Dura-Ace for the build, is
1, because that's what's on the bike already, and
2, because an earlier post suggested that was what was fitted to the actual Team Rabobank bikes.