A mamba 8.6 would be way too big. If you're in an area with a club - or have a friend with a large quiver - you should try out different boats before making a decision. If that's not an option (and I'm guessing it's not since you're asking here) then, in terms of your size, you would fit a Mamba 8.1, Nomad 8.1 or 8.5, or a new Nomad small or medium. Of course, there's no need to limit your search to Daggers (or just Dagger Mambas) since you might get a good deal on something else. My general thought is that it's best not to spend too much $$$ on your first boat, since you might soon find that you want something else, and the best course is to find a boat and get some serious seat time on the water. That's more valuable than picking the exact right boat.
I'll PM you my email address. If you've got any questions before buying a boat, feel free to shoot me an email. Good luck.