It's not a can of worms . . . it's plumbing and stock coolant flow paths. With the way you have your lines run you have tapped into the input side of the water pump (good) - but you are drawing water from the top side of the thermostat, which is the cool side of the circuit as water normally flows out of the thermostat into the radiator. On the older stove bolts this area can actually go dry between thermostat cycles. Not sure if the newer Chevy's behave similarly. This could create cavitation in the impeller (sucking air).
In the video there is also a fitting below the thermostat that appears to have the temperature sending unit. It is on the hot side of the thermostat. A tee fitting there would pull coolant from the hot side.
BTW the lines and fittings are first rate - very clean. I like it. Is your upper radiator hose entering the radiator at a place that is entirely submerged by coolant? On my '49 this is not the case - nor is the radiator cap pressurized.
If the inlet side of your plumbing is always wet - it may not really matter that your pulling from the cool side. Prior to entering the radiator this is the hottest part of the cool side. :-)
But in thinking it through - until the thermostat opens there is no flow with this configuration. It is pulling water off the top of the radiator through the intake and forcing it into the block. Until the thermostat opens there is no circuit for water to flow. :-(
But when the thermostat does open you are drawing water that was hot enough to open the thermostat in first place . . . so instead of constant flow you are getting a cycling of the hottest flow . . . which may very well be getting the job done.
