Romani: 1 family member, 2 hastati, 2 principe, 2 triarii, 2 slinger, 4 allied maniples, 1 allied cavalry. (for a 20 unit army enlarge the allied part, 2 velites and 1 romani cavalry, keeping the roman maniple the regular size).
At least that was what i used in EB1. Dont have any sources, but i do remember reading alot of posts that said that such a composition would be the most historical accurate in the EB1 forum. Since the allied portion of the roman allied was slightly bigger than the actual roman troops.