Windshield rubber gasket/seal help

[62ChevyStep]

Just had a new windshield installed, not sure who the glass company got their gasket/seal from. The seal is great with the exception of the bottom corner on each side (Highlighted), it wants to curl in and not lay smoothly up against the truck body. Is their any one specific company that makes the "Perfect Seal/Gasket" for a 60-63 windshield? We will be removing it in the distant future to perform all the body work, I would like to have a "Good" one ready for the reinstall. Is there any "tricks of the trade" that anyone knows from experience that could help cure this issue?

Thanks in advance