Hi Justin; Welcome to Permies! And A Big Welcome to Rocket Science!
Sadly, the board at grangers is not good enough for use in a batchbox at all or in the riser of a J tube.
It would however work just fine in the burn tunnel of a J tube.
I tried to use 1750F insulated firebricks in a batchbox. They completely failed in a few days!
I don't Know how close you might be to these guys
https://ssfbs.com/insulatingFireBrick.php
They charge too much shipping but their prices are good if you made a road trip.
Tell us what your hoping to build and we will guide you along the path to becoming a Rocket Scientist!