I recommend you buy Hodgdon's Varget for your first powder. I spent a lot of time working up 30-06 loads for the M1-Garand for matches. The two powders that filled the case best with the 150-175 grain match bullets and gave good accuracy and consistent muzzle velocity were Varget and the no-longer-made Scot Brigadier 4065 (so named to show it was a little slower than IMR 4064).
Varget is part of the Hodgdon Extreme powder line, so it has extreme temperature stability. If I recall correctly, these powders show almost no change in burning rate from 0°F (-17.8°C) to 125°F (51.7°C). The Varget grains are a bit coarse. For this reason I like the inexpensive plastic Lee Perfect powder measure for Varget. It has a patented wiper that doesn't cut or hang up on stick powder grains as much as my metal drum measures do. I haven't put Varget in my Dillon, so I don't know how the slide bar type of measure would handle it?
Hodgdon's manual runs Varget at 47 to 51 gains with 150 grain bullets, 47 to 50.5 grains with 165 and 168 grain bullets, and 44 to 47 grains with 180 grain bullets, all in Winchester cases with Winchester LR primers. I shoot 49 grains of Varget behind the 175 grain Sierra Match Kings in Remington or Lake City cases with Federal 210M primers. The Remington brass I have exhibits the same water capacity as Lake City military brass, which is why this load works for both. As you change case brands and/or bullets, seating depths. primers, or guns, you need to back the powder charge off by 10% and work up again to be sure you have a safe combination.
The traditional IMR 4895 doesn't fill the '06 case well. Even government match ammunition will vary 80 fps depending on whether you've tipped the muzzle up or down just before firing. This is due to the powder shifting fore and aft. It is one reason for using a powder that fills the case well.
For heavier game, look at 180 grain bullets. That is about as heavy as I would want to go unless you can test your loads at the actual longest range to be fired (300 yards for you). Some guns don't have a fast enough rate of twist to stabilize longer bullets well.