Barrels look tired. Get wall measurements before going further. And to be clear you should be looking for barrels .025 or .030 as the minimum. If they are .020 that is not a great first gun purchase. .020, with location 20” past the chamber is my personal safe to shoot minimal wall thickness. If they are .025, with those external pitting I see I would be very careful or honestly more likey to just not buy it at any price.
Here is the skinny. We do not have proof laws so tend not to understand what in proof means and what it does not mean. In proof does not mean absolutely safe to shoot. It means the bores have not been altered, on the inside by more than .010” in diameter. Which means the walls have not had more than .005” removed from the inside on both sides. The bores could be exactly like new without and metal removed from the inside and still be unsafe to shoot. How you ask? Simple, the barrels have been struck on the outside. Perhaps a dent was raised and then metal was filed down to reblue the barrels. So those lovely .025” barrels now are less than .020”. And location of thin spots is critical. The nearer the muzzle the better. Or the barrels have been refinished three or four times with moderate filing to smooth the external surface. Take a few thousands off every time and barrels can get thin quick.
Looking at those barrels I would call them tired at best. With external pitting you have to estimate how much metal will be removed to get them ready to reblue. .002-.005 would be gentle but those might need .005-.010 which could take them out of reasonable thickness for shooting.
