I have an original '68 parts catalog and the later CB/CL fiche that lists the later models.
The parts fiche doesn't show an exploded view of the CL350K3 tank, it only lists the whole tank as a PN.
The screws aren't listed in any of the docs I have for the CL350.
However, the CL175 uses the same badges and the fiche does show the screws but no one lists the PN....
I can take a look at screws on my K3 tank badges and maybe get a measurement.