I myself think the talking plan could work well. It's the best one to start with certainly. If you can get him to say all's good without any bloodshed, then you've won the battle that you didn't even have to fight. If it goes sour though, things can turn ugly with only 3 people, depending on who you bring. If you walk into his house, and find that you're in a 3v15 situation, you're going to want to make sure you can get out fast. Possibly have Jenever park a car outside the place in advance, so they don't get too suspicious about it showing up at the exact time you did, giving you a quick escape. Consider who you want the third to be as well. If none of them are magically able, Saint would look pretty unopposing, but would be able to deal out quite a bit with his magic if things got hairy. Killer-B would be good if you planned on talking, but wanted to look somewhat opposing. HB much the same,but somewhat better if you expected a firefight to break out. Exile would be best at trying to intimidate them into what you wanted them to do, but if things turned sour any survivors would remember him instantly, so it'd be an all or nothing with him. Jenever would probably be best left as recon support instead of going inside
Another thing that would determine who to bring would be if the gang has any prejudices. If they don't like orks, then who we send would be radically different, as three of our team members are orks.
Other then that, giving them even bigger problems, such as starting a war with another gang, would most likely make them forget about their encounter with you. You'd have to be careful not to be linked to it though, or both gangs can turn on you (so my character would be out for this one). If you can find out what kind of business the 405's and the Ancients do (say they sell drugs for their money), dress up like members of the opposing gang, and start selling the product on their turf. Doing it this way gives you the added advantage of being able to do more work in the area without it seeming too suspicious to the cops (a building being blown open and raided wouldn't be that out of place in the middle of a gang war) and without much investigation (just the gangs killing each-other some more).
My two cents on it at least.