Not sure, probably the 55 length. It's a Redington combo kit, so I wouldn't expect top of the line er...line.
Just went back out to the park and was able to shoot line kinda consistent, but I don't think I'm ready to try it with a hook yet. I think I'd end up turning my waders into a pin cushion. I think I'm pretty reliable out to say 30-35 ft, that has to be enough for most of the places I know of to fish, save for maybe ambleside or furry creek. But I have all winter to get ready for that. See some pretty amazing casting there for sure.
Talking with my roommate, who has fly fished before, he told me that the 'left hand thing everyone does' is called double haul, and that was definitely enough to get another 15 feet.
Rather fun, really...