I built a V8 914 and am building another now, using a number of radiators isn't new as you stated and surely can be done. Cooling is a mathematical calculation, but I have no clue how to write it out
Get the body setup and mock up your radiators, its all about taking the time and testing. Cooling a Boxster is done well so your LSx project is just a little bigger source of heat. Post some picks !!!!!!!!!!!!!!!!!!!!!!!!!