What is this "white lead" to seal the threads?
"white Lead" is lead carbonate powder in a linseed oil suspension. It was once used as paint pigment, before the tree huggers got their knickers in a twist about the alleged catastrophies caused by lead in any form. It's a naturally-occurring mineral- - -get over it! White lead is still the best lubricant for the dead center on a lathe, and I've got a lifetime supply pigeonholed away for my machining projects.
Any good brush-on sealer will work to seal the fittings where they thread into the block- - - -I prefer Permatex Super 300.
Jerry