Battleship Missouri will throw you up against Rogue GBs, as will the Essex. Malta and Ibiza like BH dessies, as do Crete and Tripoli. Missions against the Corsairs in 41 or Delta are liable to throw you against Osirises, plural. Any mission against the Wild outside of those offered in Omega-55 (I kid you not, the RM and ALG NPCs in the bar offer missions against the Wild) has a chance of throwing you against Scorpion gunboats.. the kind that makes the uber-Freelancers look like sissies.
Basically, in any system where faction x has cap NPCs, a mission against that faction will occasionally throw those caps at you if the mission is of high enough level. So, you don't get anti-cap missions from the unlawfuls in house space because the mission levels are so low, but some of the battleships will have high enough level missions to do the reverse.