I once heard the claim that the replacement loop high bridge was engineered to handle a DRGW K class.
Ths xUSG twins (GLRR 130 & 140) when operating together would be 100+ tons. As long as the 1203 was not doubleheaded against another engine it would have roughly the same weight footprint. Part of the consideration is tons per axle - 22 tons per axle for the #21; about 13.3 for the 1203; 12.5+ for the 130/140 or a 25 tonner. No doubt the first trip of the 1203 will be slow and easy checking for clearances just like we did with the 21.