Plywood?

[frayed_knot]

I know I have asked this before, but the search has resulted in nothing.

I need to replace the wood in my fuel tank cover, just like Schools did. I don't seem to have a "local" source for marine grade plywood. Can I use something else. I plan on totally encasing it in glass.

This also brings back up the whole "which resin should I use?" thing again. West Systems resin is $88 gal at West Marine and another $30 for hardener. I can go to Lowes and pickup a gallon of Elmers (poly?) resin with hardener for $35. I would think poly would be just fine and last another 20 years if done right. Any input?