Hey Guys with Magnum Air Gap

I found this 3/8 NPT to 1/8 NPT inverted flair. Hemichuck is this what you are talking about? Could I run my mechanical water temp guage with this setup and run the heater hose out of the bigger 3/8 NPT hole?

http://www.dormanproducts.com/p-3083-3204861.aspx