I’m not sure what the engineers had in mind with those silencer parts, unless
they make a more torturous part for the air to traverse the tube, and hence
silence the intake noise.
If you can tune it to run okay without those parts, I wouldn’t worry about it.
The dark carb float is probably aged varnish. As long as the float is sound,
I’d use it. I believe there’s carb kits of that era that would have a float that
works. Maybe someone can give you the kit number.