From a 22" barrel? That's going to be a real flamethrower. I'd suggest starting with a powder on the slightly faster-than-normal side for the 7mag. Your velocities will suffer a bit, but there's nothing you can do for a 22" barrel to attain 'normal' 7mag velocities anyway.
I'd suggest looking into 150 grain bullets, over 4350 or maybe even Varget for optimal results that won't leave you with a three-foot fireball at the muzzle and a 'three-day-ring' in your ears.