The thing I would be looking at given your geographic situation is the availability of ammo and the price thereof. Also, look at your funds. The 7mm Mag is an amazing round, but it ain't exactly cheap to shoot. You'll also need plenty of wide open space to practice with it, as the round is quite loud. But given that you are in Pakistan, there should be plenty of desert available for that. (And I'm jealous of you for that...)
Although the 7mm Mag will have a flatter trajectory, the .308 is capable of what you are describing. It all comes down to knowing your gun and the round you are shooting. Plus, you can probably find military surplus .308 for practicing.
I will say this about the 7mm Rem Mag, though: Make sure you have a platform capable of handling it. A good, heavy wooden stock - or bull barrel if you have a synthetic stock - is a must (if you can't really practice with it...). I have a Ruger M77 MkII with a regular stainless barrel and synthetic stock, and it kicks like a mule. I haven't had the chance to practice with it since it's too loud to shoot extensively on the hunting club (homes nearby) and most indoor ranges won't allow it. Besides, at $2.50 a round, it isn't something I can go and put thousands of rounds through.
"The best caliber and round for self defense are the ones in the gun closest to you" - My Grandfather