Be careful with that. Wood is notorious for being home to lots of beer changing organisms. While not the same as a cask, I took part in filling a 50 US gallon Jack Daniels barrel with and old ale that 8 of us brewed. It sat in there from January until August. At that point, we all transferred into corny kegs. I purged mine and hit it with CO2 to keep it safe. I just finally got around to bottling it last weekend. When I opened the keg, I found a Brettanomyces infection smiling back at me. The other brewers have reported the same thing.
I've toyed with getting a wooden cask for my Belgian ales so I can purposely introduce the "funk" from the wood. It probably depends on how many times you plan to reuse it. What state it's in when you get it, and how clean you can keep it. I think it's a very cool idea. I'm just throwing that caveat out there.
Baz