I got an old national 7 and refurbished it with all american parts, like the vent tube, jiggler, and new guage.
Since then I added new bakelite handles. It works awesome! I have an all american 921 and tried the parts out to make sure they fit first, then got parts to fit. The 921 has greater pint capacity but the national 7 works great too, it's easy to close without all the nuts, not that it's that big a deal.
It's nice to have 2 pressure canners, plus if I have to I can use the parts off one for the other.
The nice thing about the new presta pressure valve pictured is that it has a metal pin in the center so when it depressurizes it won't make a vaccume. I keep an eye on mine but it's still nice to know. Supposably it's an automatic venting valve, according to the manual, the metal thing stays open till it's vented supposably.