quarter window sealing

Reinstalling quarter windows in my 74 duster. I rebuilt the quarter windows and have the install kits, but I'm not happy with the way the window seals against the body on the lower edge. Since it only presses against the body and doesn't overlap it, there is an area for water to get behind the gasket. The gasket presses fairly tight near the rear mounting tab where the large screw goes in, but at the door end, it doesn't seal very well. I have tried to put the white foam gaskets behind the flap of the rubber, but they won't compress enough to go in. I put a thinner foam behind the gasket, and used the foam blocks to tighten the window in the opening. No matter what I do, it seems like water will get inside the body. Wish it was show season so I could look at some other cars. I do see some slight rust where I believe the gasket would leak. The way the metal is designed, it almost looks like it was made to channel the water to one location, but I can't believe Chrysler would drain water inside the body and out the rocker weep holes.