What material for Risers?

[fishmore2013]

I am putting a new floor in my 1977 20 Seacraft Master Angler. Floor and risers look like water soaked untreated plywood. I am correcting the deck drainnage problem with through transom scuppers which will require me to raise the floor 2". My question is what material do people use for risers? I was thinking of using resin and some type of hardwood. Also, will 1/2 Marine plywood treated with resin and fiberglass be stiff enough for a floor in this boat ?
Thanks Jon