Of the powders you mention, I'd use Bullseye. Using my cast Keith bullets, 6 grains clocks around 850 fps, 6.5 grains in the low 900s, and 7 grains are a little over a thousand fps.

I tried to use 2400 to make a 1000 fps load in Magnum cases, and it was a mess. Around 16 grains gave that velocity, but I was getting ES up to 100 fps, and it was dirty as hell. Never tried 800X though.