Installing new clutch master cylinder, couple of ?s

[Sparman]

Guys,

I'm replacing the clutch MC. It has an extra port that faces the from of the truck. It appears to be an NPT threaded hole, no flare. Do I just use a plug? What is used to seal the threads? Teflon dope, copper crush washer, or??

Also, I need an adapter to go from 5/16 to 1/4 for the hard line. What type fits the bill? Inverted flare?

Thanks in advance.

Curt