Here's Ed.
Agree with Steve and Tim, why? I want to go offshore and had ten plastic windows, four 5x12s and six 7x15s. Are you sure you measured correctly? Four inches seems too small for height. The outer edges of the spigot is the dimension of the hole.Hole too small is better than hole too big(my case). I had to glass in a lot of plywood to make up the difference. You will have to glass in something to fill the notch where the drain cutout exists for your Gray portlights. You won't need that with the NFMs.Use a saber-saw to cut the perimeter to size then seal with epoxy. Now the big problem. The NFMs are thru-bolted, getting the holes perpendicular to the cabin sides is an art, need to big and sloppy so you have wiggle room. Then you need a proper countersink because the outside frame has a large boss to bolt into. There are about ten of these to drill and lineup. Next is selecting a sealant and using lots of it at $12. a cartridge. Still want to do this? E-mail me for specifics.As for looks I think they will be beautiful, the S/S ones I mean. But I would add a S/S frame around the non-opening ports for completeness.And the others are right, they absolutely will not drain at that cabin angle.