Being as your bow is set for 50lbs I would recommend using a fixed blade even though a mechanical may work fine.I like the 3 blade designs.They are the most popular.For a fixed head check out Thunderheads,or Rocky Mountain Titanium's.I have used both with great success,and they are very sharp.It depends on your arrows weight as to what size broadhead to use,but 100gr is probably going to be a good starting point.What arrow are you using?How long is it cut?That will help to determine what size head to use.You may be able to use a 75-85gr head.You want the arrow to be balanced...slightly forward.I'll help you determine what size head to get.Just tell me those two things.