The COD would be our best offering for you for the space you describe. SARDINE IMHO would be too small.
When relining with a flex SS liner, make sure to thoroughly research the issue of insulating the void between the outside of the liner pipe & the old masonry chimney. What you want to do is to keep the new chimney hot/warm and not have it be a cold tube for the exhaust gasses to pass through.
We tend to check the COD about every hour or two to see what it needs wood wise.
I think that you will find that 18" off the ground is a nice height for the stove. That way you can sit down to load wood & such.