You mentioned old 6" pipe through the brick already... Can't you use Selkirk DT or similar with exhaust pipe on the inside and an air void around it for the OAK? Not sure exact diameter of DT ...
Thanks, LakeGirl! I will go through this later tonight when we settle in and wait for Santa to arrive with a big fat check to pay for the new stove (ha! I wish!). But, seriously, I will look this over before Thursday. I want to have some information on hand for the dealer so I can try and figure out what he is planning. He did mention that the Harman OAK wouldn't work (not sure of reason, will find out Thurs) but I'll have to follow up and see if he's planning on doing what you suggested.
Thanks again!!