1974 23 scupper drains

[tagalong]

Thanks for the help with the history of the Scarborough mod boat i'm looking at. We ran in today and with two men in the back, there was standing water in each back corner. After pulling back out of the water, I noticed that the scuppers drain straight down through the bottom of the hull. There appears to be some kind of old backflow preventer plug that doesn't work. Has anyone tried to 90 them out the transom and put scupper flaps, or is this standing water an issue that can't be fixed without plugging it? Thanks in advance.