Where would you place the seam? I'm thinking the middle of the p***enger A pillar. Maybe the middle bottom of the windshield. Any opinions?
Look at the gasket carefully. Lay it out in the sun and let it warm some. A lot of times a "made to fit" gasket has some curves made into it to fit the body better, and the seam will be where the manufacturer put it.
Bottom center is where I put it. Lets any water leakage drain out. If you're sure the rubber is well sealed to the body you can super glue the joint together to help with shrinkage. As mentioned, make sure the rubber is nicely warmed before installing.