I've been out of the game for a long time, but my interest has been rekindled, and I managed to convince my father to grab the Black Reach box to get him started and I'd have someone to play with. (It's exciting, because he's a renowned visual artist. I can't wait to see what he comes up with.) He decided he wanted to take the Marines from the box, but he'll most likely end up playing as Chaos, rather than SMurfs. While I'm sure the Orks will be fun, I really would like to break out my Tyranids, but I'm unsure what to put in such a small (around 600 points) list. Especially because I'm very unfamiliar with the new codex.
The Prime seems to be the appropriate HQ choice for the size of the army, but beyond that I'm unsure what to do. I love my Genestealers, but are they too expensive to take in any real numbers as troops at this level? What's the best option to deal with the Dreadnought he'll be fielding? Both the Trygon and Tyrannofex seem too expensive for this situation, but I had pegged those as the real tank hunters in the codex.