John, I'm not quite sure just what all the threads are. However, if this is the original Lockheed all-drum system (as opposed to the disc/drum Girling system of later cars), I'm pretty sure the threads are different between the two systems. Later Girling systems do seem to be more SAE, I think.
I ran into problems many years ago trying to restore the Lockheed system in my Mayflower to correct, original configuration, and I almost ruined a brand-new hard line and fitting until I discovered that one of the many cobjobs on the car had been to toss in whatever brake junction fittings a previous owner could find either on the bench or under an old Plymouth or ?????
Meanwhile, I think pretty much any of the fittings you might need are still available new, so I'm not sure I'd bother with trying to clean up anything that doesn't look pretty good already! And one other bit of advice for whatever it's worth: any wheel cylinder that aren't good enough to be rebuilt should be replaced with real Lockheed cylinders. I went through the brakes on a buddy's MGA1500 several years ago and tried to save him some money by obtaining aftermarket "reproduction" wheel cylinders. Yes, they were cheaper, and yes, they could be made to fit and function, but the fitting problems I had particularly with the rear wheel cylinders -- lots of filing of the body to make them fit properly -- convinced me that the extra money spent would've been worth it!