IMO, if youre planning on just using the house to store heat then a rocket stove with a verticle exhaust might be easier. Are you well insulated?
Building codes tend to disallow horizontal exhausts because of the issue of smokeback I mentioned before. As Satamax said, Id probably put a bell/barrel over it however there are models out there that dont have one.
As you probably know, J-tube stoves have the advantage of using gravity to feed the wood into the chamber which is what I would pick. L-tube models require you to push the wood in once in a while as it burns back.