You need to look for region locking because high definition really isn't affected for that sort of thing. PAL and NTSC only affect standard definition television formatting.
If you want to risk it, it may work. It would probably be better if you held off to make sure or contact Rockstar directly about it with this ASIN number (B0050SYILE). You wouldn't want to NOT be able to get the online portion in October.
Region locking is the high definition way to the old PAL/NTSC issue. 1080P and 720P is the same worldwide and there is nothing special about the DVD ROM. Your console's firmware indicates where you bought it and what you can play on it. There are a lot of games that are "region unlocked" but that is up to the developer...
So, Alaa... maybe you can find a workaround on google. You can either: A. Get another region console and use it for NTSC games. B. Wipe all your data and try to set up an NTSC region through the console's UI. C. Mod your console and risk losing online access to it and your account forever.
It's really not worth some of these methods. You would be better off trying to get an old used console and set it up for NTSC. This explains it in a little more detail: