If you want to defend you need to get going very fast, which is easy for you, and make him think you are running away. If you get very fast and see the distance increasing, extending is probably the plan you should roll with. But anyway, get to very high speed. At high speed nothing turns better than you and you know how Skyrr mentioned how much the 190 bleeds E? That means that when you cut throttle and pull Gs, you'll be bleeding faster than the other guy, while his high speed will be harder for him to dump. Your whole thing is probably going to get a situation where he overshoots a little bit and you can turn in an opposite heading and extend. But hey, if he makes a gross overshoot, go ahead and take your shot. You'll notice the guns on a Dora are all fairly close together, wingroots and cowl, so you can hit from a little way out.