1. I will recommend a 360mm radiator and a 240mm radiator, as that will cool more than what your components produce. For the radiator, use XSPC AX series radiators. They are somewhat slim but great performing.
2. NEVER get a bay reservoir, as there are two issues: a. You cannot use rigid acrylic because when you pull out the reservoir to refill/fill, it will disconnect. b. For normal tubing, you need to leave a little slack to allow for you to pull out the reservoir, making you use more tubing and that can cause kinks that will stop the flow.
3. NEVER get a pump/reservoir combo unless you need to, as the pumps are usually less powerful than the standard ones to save space.
4. I recommend EK Waterblocks for the GPU water blocks, be sure to get the nickel ones for the best thermals.
5. For the pump, use a Laing D5, they are the best performing pumps and are less prone to fail.
6. I also recommend EK Waterblocks for the compression fittings.