replacing your ports...
When I replaced my portlights, I called a local glass place, who gave me the names of some local plastics companies. The first one I called had the smoked Lexan in the thickness (.375") I was looking for, and cut them in a week for a reasonable price using the old windows as templates. The old ones came out in pieces and I taped them back together for the templates.
The portlights on my '87 H28.5 were "glued and screwed", and I'll tell you, taking the screws out was where the easy work ended. I used plastic razors (available at West Marine) to remove all the old sealant. That was a terrible and messy job. I tried adhesive solvent to soften up the sealant, but that didn't really work. I just scraped away at them. But ALL the old sealant HAS to be removed, or you'll have leakage eventually.
I did lots of research and decided on using Dow Corning 739 sealant, stuff they use in aircraft. The fiberglass and the lexan both had to be thoroughly cleaned with DC-OS2 wherever the sealant was to be applied. I think that hunter recommends one of the other Dow Corning sealants, but there seem to be a few knowledgeable people who say that the 739 is a newer, more reliable product, and has the advantage of being removable in case you ever have to replace the portlights again.
I had a wicked hard time removing mine...the sealant was like stone, and pulled out some of the woodwork around the ports. Use Google to search info, or search the Archives here at the Owner's site.
Good luck with the work, and I hope your ports come out easier than mine did.
Jeff