The R3 is a good pad and is a remington item that will be a factory fit. The Pachymar Decelerator is also a very good pad and they make them prefitted to the factory 700 SPS stock.
If you still have problems with recoil after a new pad, you should try a shooting vest or shooting pad that you wear. Browning and several others make them and they run in the 30-100 range.
JOE