What material/species of wood would you replace this with that would
yield a more durable result?

Dan,

Port Orford Cedar would be my first choice. The Japanese would of choice for
exposed timber structures. Needs no treatment of any kind, but questionable
paintability.

Catalpa would be my second choice. Harder to source, but better paint
retention.

Great project!

Rudy

--
To terminate puerile preservation prattling among pals and the
uncoffee-ed, or to change your settings, go to:
<http://maelstrom.stjohns.edu/archives/bullamanka-pinheads.html>