I'd try and put metal barbs on everything-those bitspower barbs are very well made BTW
-short thread is ideal for the GPU block. You seem to have ordered 2 sets which will cover the GPU block and either the radiator or res. Hopefully you've read about the issues with the EK4870X2 block-got to be careful with a couple of the screws and shorting-theyve included fiber washers now. The DD block is supposed to be a great fit and no reports of dead cards.