Update from the OP:
Thanks for the info, guys.
Yeah, I heard conflicting opinions about the make of this kamado.
A BGE company rep said it looked like one of their older models made of "fire clay" instead of ceramic, and meant to operate only up to around 400 degrees.
My final decision is not to work too hard on the rehab. I am going to try to jury-rig a new firebox out of some terracotta pots, and use it for "low & slow" cooking until I re-sell it. When I do re-sell it, it will be with full disclosure.
BGE or not, it is basically a clay kamado.
If anybody has an extra firebox they think might fit, even if used & cracked, I'd be interested in buying it if it's cheap.
Thanks again --