Of course, you have to end up with a legal point for your hunting regs. I usually start with a thin, flat flake to begin with and use a pretty sharp pressure flaker so that the flake scars travel across well. You'd be wasting a lot of rock to start with any spall that was very large. A 2" X 1.5" flake or a 2"X 2" flake should do the trick. No need to have it thicker than 1/4". I usually think of a Cahokia as a pressure flaked point, but depending on the spall, some early percussion might be in order.
