Paul, the NPOYA members bulletin board is a good place to look for answers to questions like yours. Think their web site may be npoya.org but it''s been a while.
Don''t overlook the fact that, at 13 yrs old & counting and with Pearson long gone, your boat is quickly moving into the orphan category re: many vendors sourced by Pearson. When I faced this question with our ''79 Pearson 424, I wanted to keep the cast aluminum ports & removeable screens, but all the metal screen material had been ripped. I ended up applying "No-See-um" screen material from Sailrite to the existing screen rims after trimming off the old screen material. This is just the kind of owner-type reburbishment that becomes called for as our boats age and earlier vendors & their products disappear. And BTW, we like the port screens far better - we pull them off when bugs aren''t a problem and get better flow, but we 100% seal out all bugs when we put them in. Vendor-supplied screens don''t usually offer this kind of screen material.