I arrowed a cow buff this past July. I took her with a single arrow weighing 1050 grains tipped with a VPA Penetrator 300 grain two blade head. I used an eighty pound PSE X-Force. My arrow chronoed at 216 fps. A friend shot another cow with his bow set at 77 pounds. He was using a 750 grain arrow. I cannot remember which broadhead. He had troubles (shot placement was high) and ended up killing his buff with a rifle. I really liked the VPA broadhead. I honed them to a razor's edge:
Vantage Point Archery Penetrator 2-Blade Broadheads
Good luck with your hunt!
Really you are lucky you get it in best price 2 blade on Buffalo ! go through your hunting.