Thanks for all of the input! After much deliberation, here is the final order. I changed the reservoir to keep with the full EK CSQ theme and also the pump-top. Can't wait to start working on this and modding the case a little.
A single D5 yields 4.5 psi at 1gpm when running at a full 12v.
Each video card drops pressure by 1.1psi at 1gpm. That leaves 1.2psi in 3xseries.
The CPU block drops pressure by 1.8psi at 1gpm.
Now you're at -0.6psi and still have to account for radiators, tubing, fittings, etc. That means running full out at 12v, you won't get 1gpm out of a single D5. You'll either want to get two D5s in series (which you can then run both at a lower speed), or go for an MCP35X. Otherwise, you could put your video cards in parallel; but that means that each one will only get 1/3 of the flow.
You could, of course, just keep it as-is and run a single D5 on max 24/7 and be content with somewhere around 0.7-0.8gpm too.
Except those aren't the components either ... you are quoting figures for a more restrictive CPU and in the chart you posted the EK FC680 is less restrictive than the EK supreme HF so that means less than 1 PSI at 1GPM
Edit: No Actually the 680 and the Supreme HF are about the same but still less than 1 PSI