Redoing seals on the 75 Top

[eighteenninetytwo]

I have all new seals for the 75 top. two questions.
1. Is there any reason i need to wait until I have the truck back in order to fit and glue them in place? does the cab need to be fitted to ensure the glue sets with the seals in the right position?
2. OF the two header seals that go across the top of the windshield is one attached to the body and one attached to the cab? The parts are "Header seal on body" and "Header seal on cab" so I am assuming this but want to be certain.