Both of those Gigabyte Motherboards would be fine, the UD5H is newer than the other, therefore may contain some updates the other does not have.
For the PSU, If I were you, I would grab the Corsair RM850 instead of the TX650, why ? The RM series is fully modular (easier to manage), has an 80 plus gold certification instead of the 80 plus bronze (better efficiency), also If you plan to SLI the GTX770, that would make it doable, since the SLI would require your PSU to have at least 62 amps on the +12V, the RM850 would provide 70.8 Amps, while the TX650 would give you 54 Amps for it.
I would say that the 16 GB is fine, and would keep it in that way, it is a whole bunch of memory, but that will not make any harm to it, and depending on your usage it will go really well.
Besides what tiny voices said above, I would try to get the Samsung 840 Pro 256 Gb (since is one of the best available in the market and would also give you space for your OS, common applications, some games and some other software that you may use).
I know that the GTX 780 is one of the best deals there is out there, but the GTX 770 a this point has the best cost/value, and that should be enough for a good time before SLI'ng it becomes a reality to you.
Hope it helps!