Hi Sol,
The only wood grips currently available are from Magnum Research themselves. The Hogue units.
They are not the most traditional looking things but supposedly they work.
That said, Daniel at CRAFM in your neck of the woods can make up a custom set for you. I asked him about it earlier this year.
If you need wood grips in a more traditional style that's the route I'd go.
Ruger Super Blackhawk grips only fit on the first run of the BFR's, not the JT Series. Sorry.