If you buy that host, it includes a reflector that should work with most single LED. You do not need the S2 reflector for this build.
Then, you have to decide if you want 1 or 3 LEDS.
If you want three, you have the right MCPCB and Optic, but you need to make sure the optic fits.
If you want one, you need to select a different MCPCB and LED. You can read up on the Samsung LH351D, Luminus SST-20, SST-40, and CREE XM/XP choices. There are also XHP leds, but you have to be careful because some versions are 6 or 12 volts. This XHP35 at MTN is 12v, for example.
Here are some modding resources:
Old Lumens’ Big List of Mods, up to about 2017
What Did You Mod Today?