The Berea FT Americana and RT Euro Fountain pens are available from Bill at AS in PT and TiG, and the Streamline version is available from Berea in those finishes. If metal threads are a must, that's probably your only choice. I have heard that you can improve the fit of the threads by polishing the internal cap threads with a felt bob in a dremmel tool with some EEE.
A bigger concern is if the kits still come with the plastic nib/feed and housing assembly that I got on my last order. No matter that I replaced the nib with Lou's excellent SF nibs, and fiddled with them for weeks, I never could get decent performance with them. They would go dry if they sat more than a day, and I would have to take it out and squeeze the cartridge or converter to get it started again, the ink feed was not consistant, ect. I finally had to give up on the kits completely till I can find some replacement sections in chrome. However, they are the same size section as the jr. series pens use. I also see that BB sells replacement sections, which may be the better enamel plated brass versions. That's worth checking.
