Hi Tim. Erik here, close to Bethlehem pa. I was fortunate to pick up a weber gas grill last week. Once I got it home, I realized the propane hook up is set for the old tanks. Did you have to deal with that?
Than you for documenting your screw issues with pictures, it makes much more sense seeing it close up. I'm about to embark on the same rehab on my Mauve Genesis 5000.
Just replace the connector that hooks to the tank. You only need to worry about the manifold if you replace the whole regulator. No need to do that. Simply put the ACME nut type on. Takes about 1 minute and works fine. I have updated many old regulators this way