Help finding fitting 3/4" slip > 3/8" NPT

[SWINGRRRR]

I have the DIY 3/4" BH coming out of my brute for my RO/DI water. I need help find a slip 3/4" to 3/8" NPT so I can use this valve. Any ideas? Lowes only goes down to 1/2" thread and I checked aquatieco.

http://www.rosystems.com/reverse-osmosis/water-treatment-products/J-0620617.html

 

[THE ROOK]

You'll likely need to go down in two steps, thus two adapters. Might even take three pieces.