From your post it looks like you are determined to SLI! It is better to use one powerful GPU than using SLI. Not all games are SLI supported and you'll need good PSU as well. Anyhow, if you have budget then 770SLI, otherwise my recommendation is to use one 780 or 780Ti. Rest is your choice. Pl keep in mind that PSU should be good enough in terms of efficiency (Load an Stress).
You may consider Corsair AX760W (80+ Platinum) or CS750W (80+ Gold) or GS800W (80+ Bronze)
Have decided on SLI GTX 770 4gb (1 card now + one card soon after)
Finally the Power supply I have picked out (and posted before for input) is a
ANTEC TRUE POWER CLASSIC 750W 80PLUS GOLD. UP TO 92% EFFICIENCY, 2X HIGH CURRENT +12V RAILS. 6 X 6+2 PCI-E. 20% ENERGY SAVING >80PLUS
Power components will be 2xGPU (obviously)
i5 4670K Oc'd to 4.5ghz (ish)
Corsair h100 Water Cooler or the H100i (the 280mm one)
2x Samsung 840 Evo SSD 120gb
2x Sata HDD's
1x bluray/dvd/cd W/RW
4x Case fans (140mm)
Motherboard is Asus 787 Expert
Writing this off the top of my head so I hope I havent missed anything,
If anyone happens to stumble upon this again and notices any problems with proposed PSU please comment.
I will list my complete build on here once It's ready to be purchased for final checks.