The light you list is made for compact autos. It will fit but it is kind of petite for such a big revolver and will have a long distance between your trigger and activation switch. I stuck a TLR-1HL on mine. It really lights up the area but it is still a reach to activate the switch. That's the big problem with installing a light on an R8/TRR8 - the barrel length puts the activation switch out of usable reach so you either have to alter your grip or use your off hand to flip it on. Not a huge deal but a bit different.
