The before and after on this 1970s masonry stove was wild, took 3 days

Got a call from a lady in Portland whose grandmother passed and left her this big old masonry stove in the basement. She said it hadnt been used in like 20 years and wanted to know if it was safe to light for the holidays. I opened the cleanout door and honestly couldnt see the firebox wall, just packed soot and what looked like a bird nest mixed in. Took me three full days with a shop vac, rods, and a lot of patience to get down to the brick. The difference between day one and day three was night and day. The draft went from barely pulling a piece of tissue to pulling a whole newspaper sheet right up. She watched me do the final scrape and said, "I didnt think it could ever look like that again." I feel like old masonry units get written off too fast when really they just need a deep clean and maybe a new door gasket. Anyone else run into a stove or fireplace that people wanted to tear out but just needed serious cleaning?