All Nighter Stove Works "Big Moe"

I am a first time poster but long time wood burner.
This wood stove was used to heat my parents house over 30 years ago. Since my parents don't use it they asked me to please remove it from their basement. This thing was so heavy I was afraid rolling it up the old basement steps along with the weight of the people moving the stove could collapse the stairs so we removed the firebrick and the board between the brick and the inside of the stove. The 3/4" board crumbled as it was removed and 5 of the firebrick were cracked. I am in the tree and landscape business and keep our equipment in a 70' x 50' pole barn with only portable propane heater with a concrete floor and 15' ceiling. Make a long story short, we are installing the Big Moe in the barn. The firebrick were easy to replace but the board that crumbled is proving much harder to find. Any help would be appreciated. Here are a couple of pictures. Our local shop "The Woodburners,Inc" is helping me with the chimney as I will post pictures as we proceed with the installation. All help and comments are welcome. Thanks