1968 Philips/Corning Windows were an attempt to be the most improved/serviceable design of the three year series.
1966-1968 window curve has an increasing radius from top to bottom.
In the second image it appears from the ID etching, that your glass is installed up-side down. The original glass ID etching is in the lower left corner as you face window from outside.
Does your preferred grey color weatherstrip have enough loft, flexibility and sealing pressure to compensate for the dissimilar curvatures of glass and window frame?? Was it recommended or advised by the replacement glass supplier?? Does it seal well against wind driven rain?? Does the grey weatherstrip have UV inhibitors, Is it open or closed cell foam?? Can it be scrubbed clean?? Does it need conditioning with Aerospace 303 to prevent sticking??
Upon re-installation, is there a reason to omit the stainless steel tabs at the ends of the clamp-bar??
What advantage has silicone over the approved foam tape method??
Hint: Utilizing the stainless edge trim hides from view and protects the weatherstrip from sun. It reduces glass breakage from edge impact, and provides a more finished and matching original appearance to the window.