Hi, I don’t know the 1st Corps Republican Roman range but assuming they are the same size as the Imperial Roman range I would think they are quite small. From what I know they were sculpted to be compatible with the early Foundry ranges but are not compatible with the later ones ( eg anything sculpted by Steve Saleh). The Foundry Republican Romans were sculpted by Dave Gallagher and I don’t know where they fit in the growth from 25-28mm.