I'd use that setup for dangerous game..... as a monopod for my .600 Nitro double rifle!
I would venture to guess most everyone would tell you the same thing. Your setup needs more "beef" before heading after dangerous critters like Buff, Big Bears, and the like. A lot more arrow weight, and enough horsepower to get it going a sufficient speed to do the job. Every animal has got bones that will stop most arrows, but animals like the Buff have them covering their vitals. Their ribs are substantial and have to be broken by the arrow for it to do its job.
I'm not going to venture to guess what it takes to do this, but a good "test" would be to shoot your setup into a 1" x 4" wood board. When you can pass through that board you are getting in the neighborhood of where you need to be. I've got a bow that has shot an arrow through my pretty well shot up bag target and two 1" x 4" wooden boards (I.E., my doubled fence), and then skipped 35 yards out into the adjacent field. And I wouldn't carry this setup, as is, after a buff! 78# @ 29", 800 grain carbon arrow. I'd up the weight of the arrow to 1000 - 1100 grains and depending on what the speed was of that arrow I may go to a different heavier bow.
They are big and dangerous critters, and would be a dream come true to take with a bow. To me it would be a nightmare to stick an arrow in the near side rib and have the PH shoot the PO'ed bull with his rifle before he stomps you or him into the ground. But, that is me.