I was looking at my portlights. The bronze is awesome, and will likley clean up very well. That said, there appears to be no gaskets on the inside of where the portlights are opened or closed. It looks like there was some gaskets in ther at some point, but over the past 40 some years has disolved. Without the gaskets, it's just bronze to bronze mating in the channel where the gaskets probably used to be.
I tried to buy some gaskets through Amazon, but haven't found anything that works. The picture below shows the empty channels. What did you do about those gaskets? These are the rectangle portlights from the I31C.