Re: Shower Pan
We replaced our teak plywood head sole with a Teakflex grate several years ago and are quite happy with it. The grate is comprised of slats that run fore-aft and are screwed and bunged to athwart stringers. We've varnished it for ease of cleaning.
While you are redoing your head, be sure to facilitate scum removal from your sump. Standing gray water can generate some funky smells after a week or two. Our whole grate is removable for this purpose, but is also has a removable section that allow us to readily access the deepest part of the sump.