I know of only one PAR meter in the club, maybe two, but I have not heard that they are any good at metering LED lights; similar to how well a digital camera captures a pic under LEDs. I'd be curious to know how successful this works out. Please let us know. 
Personally, I'd be more confident in simply trying to match the Radion intensity from memory, then turn it down some and do the normal acclimation slowly upwards. The coral will show their favor by their response to the new light.
Aloha,
Mark 