I have a Hunter 40.5 (1995) whose aft berth cushions need to be replaced. They are 4" thick. Might someone first of all know what density these original factory cushions might be (I see foam at uphotstry shops with rating like 40, 60, 70 with the higher number being harder. Some of the samples say HC 60 and other LC or LO (I couldn't tell) on them. What might that factor be. Appreciate any advice. tom