Late model master cylinder fittings?

Hey guys,

Finishing up the 4wheel disc brake swap on my 71 Plymouth scamp. Not sure if the fittings I have in the late model aluminum master cylinder are correct. I’m using the one pictured below for the rear port, I’ve tightened it a good bit but I swear it seeps a small amount from the threads. Is this the correct fitting to use? If not, where can I find the right ones?

Thanks!