By all means, consider using that large bolt and an extended stud bolt like Bird Brain said, to hold a bracket for a band brake--but it will have to be custom I think. You need at least two anchor points/screws.
I had a Briggs that had a tapped hole in that bolt/hole location just like 71demon's engine; it was on a front-tine tiller engine and even though it was a huge bolt, it was used to mount a bracket there that held the idler pulley, which in turn pivoted onto the belt to tighten it and engage the tines.
Furthermore, on more upscale tillers (snowblowers too), that hole is a bearing for an extension of the camshaft that goes through it to the outside, has a pulley mounted on it and which provides reverse power (since it spins in the opposite direction). The tapped hole and the bearing hole that goes all the way through the sump cover is directly in line with the camshaft. But I digress and babble...
I guess make sure the hole that bolt is in doesn't go all the way through. If it does you have a potential oil leak there if you don't use a thread sealant.