I assume you'll make an external orifice for testing the pressure drop?
Like two thermostat housings bolted together, I mean, w/ the t stat between them, varying pressure/temp?
Could you also try varying mixtures of coolant/water or different types of coolant? I believe there is a viscosity difference, which could change hydrodynamic profile.
It would be great to find out that by varying your coolant mixture by 15-20%, you could get better efficiency from your engine...
(Dreams, right?)