I have used a cast Lyman 358156, 158 gr. gas checked SWC over a near max charge of 2400 or A#9 on deer. I'm convinced that a cast bullet is best for me and the way I hunt, JHP of whatever extraction always seemed a poor use of resources(money). Another feature of cast is lower friction coefficient, consequently higher velocity, all other things being equal. If you don't cast your own check out Cast Performance Bullets. I have used them in bigger bore revolvers and Contenders and quite liked them, but they are pricey.
My opinion of your use of A#7 for 158 gr. bullets is that you would enhance your performance with a slightly slower powder in a 6" barrel, hence the 2400 or A#9.
Another factor from my side is that I've never used a S&W for the purpose you describe. I used Ruger, Taurus, Colt and 10" Contenders.
Good hunting and good shooting, fill your tags!!!