Well, I just got the word back from a contact at Polaris Factory...
Looks like the different thermostat is the best bet to do the radiator/cooler delete on the 600's and the 700's in 2006 thru 2008 small blocks.
Plug off the bypass line on the head under the thermostat housing and install the 2008 163" thermostat # 7052452, for the coolest running of these sleds without damage to the pump or seals. This will also eliminate quite a bit of heavy plumbing with coolant in it and clean up the underhood appearance a bit. Probably leave the "inspection" hatch off of the radiator accesss to allow any of the air that might make it thru into the engine bay where it might do some good.
As a note to those who dont speak "bypass"... This is the line that lets enough coolant flow thru the motor to keep the pump and other seals from blowing out and allow a bit of circulation inside of the motor once the thermostat closes.