Since you said 'urgent need' I'll assume you're looking for a quick fix as in make it safe to go offshore
. Try this:
Drill and tap the frame for a bolt or machine screw to hold the port closed. If you're careful you may not need to remove the frame. Use a blind tap to finish the tapped hole. Glop up the end of the screw with some sealant
and screw the port down. Safe to cross an ocean until you find a replacement or do a proper fix.
Doubt those ports
are being made today but you could try some of the consignment houses, such as Bacon in Annapolis
MD, that may have an old one.