No 'scientific flowrate data' unfortunatly, but just some simple observations of how fast the water moved in the radiator with the thermostat and cap removed.

I recall having tried 3 or 4 waterpumps; 2 factory cast iron ones, and I think 2 alum. ones. I also changed between a cast iron and alum. waterpump housing back-to-back but found no change in 'visible flow' or temp change with the same waterpump.

Also tried to make sure all waterpumps were installed at the proper depth, so the impeller was just a 'gasket-thickness' away from bottoming out in the housing.

The engine I was working on at the time was running hot and I wanted to know if the waterpump or housing could help with the situation.

What I did find was that the 2 aluminium waterpumps with scroll type impellers didn't move the water all that fast when the engine was revved.
But when I installed the stock cast iron, stamped impeller waterpump the water came rushing by like in a washing machine.

Also did find out that not all waterpumps are/were created equally, eventhough they carried the same part/casting numbers.

These are about the only pics I took at the time;