I am trying to seal a wall mount faucet for a lavatory/bathroom my wife purchased from Morocco. We live in the US, but the thread on the moroccan piece is BSPP G 1/2. I got some G 1/2 dowty sealing washers (steel band with a neoprene gasket inside, and that worked to seal the connections on the valve body, where I'm going to an BSPP to NPT adapter and from there on down the line with PEX plastic pipe. It also worked to seal the faucet connection to the valve body. Body on this piece is concealed in wall, and the tap and two tap handles all thread into it. Problem is the tap handle threads are very short, and the G 1/2 dowty sealing washer doesn't fit and still allow me to start the threads on the handles. What are the pro plumber tricks for sealing something like this? I tried a double wrap of Teflon tape and it still leaked a little when the handles were open. Pipe dope? Loctite 577 or 55? Thank you!