I got this one!
The trick is to match what the combination of the block and rad will do, at different flow/pressures, then "overlaying" this new curve with the pump's, to see where the lines cross. (the error is the pressure drop from the tubing, but it should be negligeable, with proper precautions).
BillA's radiator testing
(Use the "Surplus" unit's curve, because although the bigmomma is the same as a chevette core, it has restrictive fittings)
Add the curve to your block.
Then find the pump curve (see
pH's sticky)
...and proceed as described.
For conversions, use
http://www.convert-me.com