If we are talking about a wooden mk1 boat I would be wary about installing screw bungs or even socketed plastic bungs. The bottom of the transom is a notorious rot spot and the holes drilled into the bottom that accept corks or rubber bungs will remove water almost down to the last drop. If you install a screw bung you will move the bottom of the hole up several milimeters and will trap a surprising amount of water on top of this vulnerable area. The push in plastic ones are better but it’ll still trap more water than leaving as is.
Tight fitting corks in my experience are fine 🙂 I can count on one hand the times ive had one come out in 20 years of dinghy racing