The 970 is a lot better then the 770, and uses somewhat less power. The 1200w power supply is probably overkill unless you intend to 3-way SLI in the future. You can probably drop it down to a 850W or so and save enough money to pay the extra for two 970s instead of two 770s. Two Gigabyte winforce OC's running full tilt will consume ~500W of power, leaving a healthy 350W for the rest of your system. Should be fine unless you intend extreme overclocks.
I agree on the heat sink, except it seems like you already own the heat sink. In that case, stick with it.
Finally.. You are spending 2200$ on a PC. Where is the SSD?