Atlanta Stove Company Model 20

I would be suspect about that installation!
It looks like the legs have been removed, and if so, that flunks big time.

I seriously doubt anything inside the brick could have or would have reduced the clearances.

At a minimum, you should use the NFPA generic wood stove clearances and also make sure the stove has legs. You can probably find some replacement legs at a stove parts place like Woodsmans, etc.

Safety is always a concern, even with occasional use. What if the power is out for a week? Will it be depended on then?

Standards are not based on amount of use. An illegal and unsafe installations is purely that. It only takes once to burn down a place. I myself, in my younger days, burned down a shed and ignited a floor by unsafe installations.

Basically, it should not be used at all until it can be rendered or proven safe.

FYI, I also inspected a house recently for an insurance company - a million dollar house which had the major fire. They also had a fireplace they hardly ever used. Well, one day the power went out and they fired it up nice and hot...and the weaknesses (not built to code) came out....it ignited the wood in the walls.

Looks unsafe to me in a number of respects. Most particularly the brick appears to be applied diredtly to the (presumably) combustible wall behind, the stove seems too close to the brick, even if it were built as an approved wall shield, with a 1" airspace. The floor protection in front of the hearth looks questionable. I don't know anything about the stove...if it's s'posed to be supported up on legs, then that's a non-starter. I wouldn't ever burn in that stove. I'd scrap that stove. If I wanted a woodburner in my home, I'd start with a clean slate...even if that meant a lot of nasty rip-out...and make sure it all got done correctly and safely. Proper installation of a solid fuel-burning appliance is nothing to cut corners on. They can be wonderful heaters, and they can be brutally unforgiving if not put in just right. Rick