It sounds like in low-draft situations, he can smell smoke in the room. For the 'stinky dog butt' theory to hold, I would think you could only smell anything if your nose was right on the dog's butt, not across the room.
For sure, I'd try the glass gasket if that seems to be where the smoke is coming from. If that doesn't work, offer to sell the BK to your brother...if he can install the stack with no bends. If he can get another foot or two of chimney on the top, so much the better. It will probably work (not sure if the 30 is worse than the 30.1, but both have had odor problems IIRC.) Better yet, sell it to some sucker you don't know, that hasn't done his homework.
Seriously, I would probably ask a potential buyer what their chimney setup would be, and tell them they really need to adhere to the installation instructions. You could sell the dog's butt for 1/3 off, and for that money still get a new Ws Ideal or Absolute, which I'm pretty sure
would work on your stack. Me, I'm not willing to put up with any smoke smell so I'd be making a move, if I determined that something else would meet my heating needs. When dogs start following me around because I smell like their barbecue-chef owner who gives them meat treats, that's where I draw the line.
BTW, what Ws stove does your dad have?