Don't forget AA3100. Any of the listed powders will work great for you in 7mm rem mag. You might lean toward the 3100 or 4350 a bit since you are going to use 140 gr bullets. As to H and IMR being interchangeable-they are ONLY after you start a little low and work up. Different lots even make a difference. That's why I like the idea of buying 8 pound kegs.