General rule of thumb from what I've read (not that I am a super experienced water cooler) is one 120mm rad per component. A 140mm single has about 70% of the surface area of a 240mm rad while a 180 single has about 113% of the surface area. I'm sure having a thicker rad, better fans, etc. can mitigate things to a point and perhaps this would be adequate for your setup. I think if you were to use something like an EK thermosphere on the 1060 which needs relatively little dissipation when compared with the Nano would probably work. Furthermore with a bit of tweaking you could probably underfoot your 6600K without compromising performance depending on your application.
Also with respect to your power supply choice, it actually appears to be larger than a standard SFX power supply by about 50% (215 x 113 x 49 mm) vs (125 x 100 x 63.5), have you considered just using an external SFX like MarcParis did in his S4 Mini Build?