Jason: If I reall correctly, the most I tried in my .72 was 150 grains of Goex FFg under the 835-grain conical.
With black, the finer the granulation, the higher the pressure. Fg, normally the coarsest sporting grade, will give the least pressure and the most fouling, generally, but would be fine in the .72. I preferred FFg for a bit more velocity and a bit cleaner burn. Never tried FFFg, but you could try it with lighter loads; I would be a little nervous about getting much beyond 150 grains with FFFg. Four F (FFFFg) is priming powder for flintlocks, and could well destroy a Kodiak with its rapid pressure peak.
Most shooters say the Swiss brand of black is more powerful and clean burning than the Goex, but Goex has been working hard to improve its product, and it is good stuff.
I don't care for Pyrodex or the other substitutes, as they are usually harder to ignite and have fouling/corrosion issues of their own.