We are in the process of building a temporary hatch for our N28-II. I am building the temporary hatch so that it is fully functional as it is likely to be on the boat for several months as I work on the original one. Ours is fiberglass that used to have what appeared to be a plywood insert on the top. I finished pealing the plywood layers off a while ago, and it definitely needs attention. I will be adding another layer of glass cloth and mat, then building up the top surface with teak decking slats. Here is what ours looked like after removing the plywood.
"Sailor James" on youtube has a great series on the replacement of their forward hatch. They replaced the hatch with a new Lewmar. Ended up looking really nice. I'd go that way. Would look nice on a N27, especially if you went with a more flush mount and got rid of the box riser.
We had a Neptune 24 before our current boat. It had a really nice translucent fiberglass hatch that fit the contour of the cabin top...I could never figure out why they didn't do something similar on the N27 since the topside design on that boat is so sleek looking.