I've had good luck with cast bullets in my .357 Maximum Handi. The bore slugs .357", but I'm currently sizing them to .359". The gas-check Lyman 358627, 215 grains, seems to be a good bet for a deer bullet. I have tried the Lyman 311041, a flat-point GC bullet of around 170 grains weight, in my .30-'06 Handi. Results have been okay so far, but the cold and snow up here in Wisconsin have put a damper on load testing recently. Reloder 7 is the only powder I have tried so far in either round with cast bullets. It's the slowest powder used in the .357 Max, and one of the faster ones for the ought-six. It does yield a good reduced-power load in the .30-'06, but a really mild load can be made with a pistol powder like Unique. Another really good powder for the ought-six is SR4759, now distributed by Hodgdon. If you can find it, it makes a wonderful mid-power load with 150 to 200 grain bullets in the .30-'06.
Consult the Lyman cast bullet manual, or as mentioned by Stimpy, the Lee book.