If it helps, I used to mod Halo 1 and have all the models from the first game, converted into .blend. I'm not exactly sure on the legalities of this though, plus they'd have to be heavily modified to look decent, as well as some better quality skins than what came with the game. I've also got a bit of experience with 3d stuff/sfx but I'm not sure how useful I could be...
Here's some pics of some of the models (the high poly ones from the game):
Also, here's this short animation I made when I was bored a while back and still learning stuff...
Youtube link
Absurdly large file, better quality (no compression if I remember correctly)
I know none of this is too amazing, but I'd be willing to help out if I had the time, or at least try to learn more to reach a point of being useful.