The hubs on a 256mm MK2 16V are completely different to the MK1 hubs and as such the caliper carrier wont bolt up the your hub.
What you need are a set of 256mm discs and pads, and a pair of hopefully rebuilt calipers.
Then what you need is the caliper carrier from an audi, I think the early coupe, 90, Quattro etc have these and this takes the 256mm caliper and yet bolts up to your original MK1 hub.
also all MK1 hubs are the same regardless of whether or not the car is a 1.6 or 1.8