The Sugino AT is designed as a triple, with two bolt circles: the outer one is 110mm for the outer and middle rings, and thus the smallest ring that will fit is 33T. The inner bolt circle is 74mm, and can go down to 26T. In order to make a 42/28 double, you'd need to run rings on the inner and middle positions, and leave the large ring plateau empty. But you'd still need to use a triple-length spindle to get the needed clearance for the 28T ring.

A better solution would be a crank with a smaller bolt circle, like the Stronglight model 99 or its Sakae Ringyo clone with 86mm bolt circles. You could then easily build a 42/28 compact double.