IIRC, max number of men in a unit is around 250. It is not possible to go over that because it's hard-coded. The number of men in export_descr_unit.txt is based on normal unit size. So, if you have 60 in the file it means that playing on Large will give you 120 men (2x60) and on Huge 240 (4x60).

You can find more modding info in here: Modding Questions