Here is a shot of the original bracket the pins go into. They push in and then fold over like the old binder brads. Some but not all vendors sell this type of headliner for the screw in center bow cardboard sets. American Classic Parts is one that does. The original bracket sets are quite rare now as most original headliners are long gone.
https://www.flickr.com/photos/advance-design_parts_co/16449458856/in/set-72157631868452754The screw-on weatherstrip and "T" is not designed for the weld on tracks. You are trying to mix two different assemblies, I believe Carl was on the right track, pick one. The way your truck is configured is really for the floating center bow based on your weatherstrip.
https://www.flickr.com/photos/advance-design_parts_co/9531186115/in/set-72157631868452754https://www.flickr.com/photos/advance-design_parts_co/9531186671/in/set-72157631868452754One more item to check and date your cab. You will notice there is a hole in the dashboard (upper LH corner to remove the screw in the weatherstrip. There is one on the RH in the same location.
https://www.flickr.com/photos/advance-design_parts_co/8625359671/in/set-72157631870734114Trucks built after mid-49 I have not found to have these holes and they have the spot welded channels.
https://www.flickr.com/photos/advance-design_parts_co/8130538304/in/set-72157631870734114
