If its orb the 45 should screw in preety much all the way in easily. If they are right for each other they will screw in just a few threads. Teflon pipe dope is all you need. No cure time needed. Make it tight. No leaks
As HHG stated they don't stock those fittings with the ORB thread and I did buy them from them so I agree that the ORB threads are ruled out.
HHG- Wanna take those 2 fittings into your lab and give me a idea of how many cranks I should be giving them?