Possible Sources
Looking at some of the posted photos of that era 27, the rear-most port with the sloping aft edge looks like the one on my 78 H30. The rectangular one forward of that looks similar in construction. I believe these were made by Marks Plastics, their info can be found using an Archive search. An alternative is Bomon in Canada(website www.bomon.com). They will custom manufacture ports of any shape or size. They are aluminum frames and either Lexan or tempered glass. Run an archive search on Bomon and you should find some previous info I have posted. At the time I ordered mine, they were only about $20 each more than the plastic framed units from Marks with similar delivery.