My boat came new with a Gray Marine forward hatch. I don't think that O'Day used Beckson but I could be wrong.
What I would do is remove one of the port lights and seal the opening with something just temporarily. Take the port light with you to some stores and try to match it up with something made of Aluminum.
Years ago I removed my forward hatch in the fall and covered it with a piece of plywood. I covered the plywood with a small polytarp and covered the boat with my large polytarp. Then I took the hatch to a marine consignment shop in Newport RI. In the end though, I wound up buying a used Gray Marine hatch off Rudy and I rebuilt my old hatch. I recently replaced the lens in that hatch just last summer with the boat at the dock. If you can go with Aluminum, go for it.
Good Luck!
Joe