I ran a sealer under the pieces as I was attaching them and a very small amount around the edge just enough to allow water run off but not be visible.

I did a roof on a 1934 Ford a few months back. We didn't want the typical look so we came up with this. We shaped a thin board to fit over the bows an counter sunk the screws to hold it down. We slowly shaped some plastic trim from the hardware store into the channel and screwed it in from inside like the original pieces would of been leaving enough room to tuck the material in with to much gap. We then padded the roof and sanded it smooth and wrapped it with our material. Makes for a clean look without having to modify the car. I had close to 20 hours in the job from start to finish.