[swamprb]

I've never used anything labled refractory cement, only furnace cement, so I can't speak for its healing properties, but If I were restoring this pot, I'd just use JB Weld and try to run the cracks and fill them in with the epoxy as much as you can. So #1 is my vote.

The problem I had with your repair plan #3 was, I thought it would also be the best of both worlds repair until I painted a pot and it kept peeling off the areas covered with furnace cement. If you can get the refractory cement cured in a kiln it might work for you. IMO they are not worth the expense to try and get all worked up over.
Big money spent on repairing or replacing parts on a 40-50 year old Kamado would be a better investment just buying a new Big Green Egg, but a couple tubes of JB Weld and a few rattle cans of paint won't break the bank.