Ok, was going to wait till this Spring to waterblock my 780Ti classies, but got tired of waiting for the snow to melt!
I went with EK waterblocks, but stuck with the EVGA 780Ti Classy backplates and thought I'd share how it all came together.

These are the screws I used - ordered them from Mr. Metric. They worked perfectly to secure the EVGA 780ti Classified backplate to the EK waterblock and look great. I installed the EK block per instructions, but note that I used the M3x8 screws to actually secure the EVGA backplate to the EK block. The M3x6 screws are strictly for cosmetics - I used them to plug the EVGA backplate holes that don't go anywhere, i.e. the ones with no matching screw holes going into the EK block. (Tip: Use a small BB sized ball of poster mounting putty in the EVGA backplate holes that don't go anywhere - this will help secure the screws in place and keep them from falling out or rattling around. Strictly cosmetic, but looks a lot better than leaving empty holes unplugged in the EVGA backplate.)
Here are some more pics:




I'm really happy with how it all turned out. The EK blocks and the EK terminal are great! The GPU's are nice and cool now... idle at 19C and only hit 35C under full load.