I go with the base T1 rules, standard, on the Eden site that's used all around. Much easier to do, especially for these types of battles, and yeah. This'll be a fully realistic battle, no magic, no superpowers, no advanced races, just humans of specific skill sets and equipment duking it out in some way. Can put in small bands of NPC types to have a interesting mix of RP between unit to unit, which our characters being the most skilled of the lot, and if your char encountered the NPCs then you can kill them off as long as it feels realistic about it according to natural skills, like it wouldn't make sense for a gaul to easily dispatch a Spartan Hoplite like it was nothing in a fight, unless it was a backstab or something, so some good detail explaining how the fight went down, long or otherwise, then continue.