My BROOKS 50 caliber mould is a copy of the boolit designed by John Hansen, from Sand Hills Ranch; one of Ted Turner's buffalo ranches in the Nebraska sand hills. He did an article in BLACK POWDER CARTRIDGE NEWS about his experiences guiding buffalo hunters and what calibers and boolit shapes worked. (I'll try to find it somewhere in my stacks.) I haven't shot a buffalo with it...except the steel one at 800 yards at the Quigley shoot. 610+ grains in 30:1 and about a .300 meplat. The KALYNUIK paper patch mould is similar to a postell. I have high hopes for it at the Q next summer.
For hunting, I'd refer to Mike Venturino's SHOOTING BUFFALO RIFLES OF THE OLD WEST and several articles in various magazines. Bill Bagwell (Redneck at GOEX web site) made some interesting comments while I was at the Q and he posts at both shilohrifle.com/forums, as well as at GOEX. There's a lot of information out there on the web sites, especially for the 45 calibers. There just aren't very many "instantaneous kills" with black powder rifles.
I think you're on the right track with one boolit for target and more specialized shapes for other purposes. I just wish I'd ordered the mould from Rick last winter, but I was "chasing my tail" sorting out a lot of data and opinions from knowledgable persons with experiences to back up their theories.