I've built my own 700c rims onto mtb disc hubs on my winter road bike, and have no problem with the brakes being too powerful for road tyres - in fact, it is easier to control the braking power right up to the point of loss of adhesion because the disc brakes modulate better than calipers. I...
Looking at the picture on the Pinarello website, I think I've spotted the major difference between this and an original "old" retro bike:-
There is definitely modern technology hidden within this bike, look at the way it hovers!
I remember them - the discs were chrome IIRC, and just didn't bite at all when wet - which meant a good second or two of absolutely no deceleration until they dried, by which time you were hauling on the brake lever like mad, and you suddenly got the full braking power - a lethal combination on...
Living in Keswick? I wouldn't like to go down the Struggle into Ambleside without disc brakes (not just because of the braking power, I don't like the idea of my tyres exploding through the rims - I weigh roughly 100kg, and all the potential and kinetic energy has to be converted to heat at some...