Help with an old cook stove

[Squiner]

My parents have this same old cook stove in their camp. My dad wants to get it operational so he needs to add a flue. Its got an oval output equivalent to 8" round. He would rather use 6" because he already has some double wall from his other install. Can he just get an adapter and be done with it or would you recommend he pony up the cash and go with 8"? Will it not perform as it should with 6"?

8" seems quite large to me since the firebox is the small square door at the top left of the lower section. The firebox cannot be much larger than about .75 to 1 cf.

Thanks for any insight

(broken link removed)

 

[Squiner]

that stove probly have a lever which redirects the exhaust so it goes under the oven when its heated up adequately, good 4 baking & heating the whole mass. downsizing to 6" might kill this function. no prob otherwize ithinx

I just talked to my dad. He says they do want to bake with it. He also spoke about the lever to redirect the gases. I think you may be correct, the redirect may need the extra draft from the 8" to overcome all that resistance.

Thanks