After trashing my first Ron Davis radiator, I formed some strong opinions about good grounds and isolating the radiator.That would seem to be a point against grounding the radiator.
I had accidentally grounded the radiator via the lower radiator hose anti-collapse spring. It touched both the water pump and the radiator outlet, completing the circuit and allowed voltage in the coolant to return to the engine and then the battery, taking bits of aluminum along with it. It only took two years to convert that radiator into a great piece of wall art.
In addition to trimming that spring, I added a big braided ground from the engine to the frame, and ties to a piece of hardware that contacts the water jacket.
I forgot the exact tolerance, but something like .15V is the upper limit when measuring from your coolant to an engine ground. I think I ended up at a resting 0.09V, and spiked to 0.11V during cranking.
All this to say, I recommend isolating the radiator entirely, and creating a series of good and interconnected grounds so the coolant is the most resistive path back to the battery.
David