I have found a source for polished bronze ports that should fit easily in the v-berth. I measured the one that is in the head against the external measurements they provided and they were identical on width (10.25") and within 1/8 for the height - theirs is 7 3/8 and mine is 7 1/4. Since I can send them back just in case, I ordered two.
The source is
Whitewater Marine HardwareThe person to speak with is Curtis Wallace. Or e-mail at firstname.lastname@example.org I am skeptical of the last "d" the address. Seems like it ought to be an "e" where there is a "d" so there might be a typo in what I got on the internet. Maybe not, of course.
I can now report to anyone who is interested that in the opening ports from Whitewater Marine Hardware that they fit just fine in the hole Whitby used. Neither cutting nor fiberglassing is required. Maybe a little putty at the most. I dry fitted one yesterday and all went well. The fore and aft screw holes on the trim right lined up almost perfectly with the holes on the WWMH trim ring. There may some merit in creating an inner spacer - because the width of the cabin wall is 3/8" - I understand that doing this will strengthen the instalation. I am pretty sure is is easy to do.
Here is a photo of the opening port I purchased from Whitewater Marine Hardware. Ignore the stainless steel bolts - that was just for positioning to see how they fit.
Also, for those who are interested, I also found that Spartan Marine in Maine makes an oval bronze port that looks like it will fit into the v-berth holes with very little cutting - no filling in, I think. The price is $241 per port. They do not discount because their margins are very tight - have not adjusted prices since 2001 I was told. The person to talk to there is Paul.