It seems to me that most crossbows are in the 150 range. Maybe I'm just out of the loops as I have a recurve model and seems more and more are compound models now days. That being said, they don't have any more power or range than your standard compound/recurve bow. Just the advantage of being cocked and locked.
I would think any quality 2 blade broadhead would do. It's all about a sharp broadhead and shot placement. You double lung them with a practice point..they're still going to die....it's just a matter of how fast.
Personally I'm not a fan of crossbows, just because they are so heavy and bulky...but that's just my personal opinion.