I'm a little confused... are you looking for some one to teach both Niten and Aikido? Honestly, that can be rather hard to find, Koryu are, at the best of times, a rarity to find, let alone a teacher who teaches exactly what you're after in combination with another thing you're after.
The first thing to do would be to ask why you're after these systems in particular, then to look around at what is available in your area. Koryu tend to require sacrifice, and they're not just around the corner. For a great number of systems you need to move to Japan. That's it, really. So how bad do you want it, and how far are you willing to go?