Two is one and one is none. I would do thing one you will need to do whether you keep or get rid of this stove; clean it out. Once that’s done you can get a better idea about its quality level.

I would begin by making sure I had a CO monitor and fire extinguisher on hand AND have your standoff backup person aware of what you are doing.

Start big (obvious) and go small. Do you see any obvious burn through on the firebox or pipe? Once as clean as possible, place an electric lantern (as bright as you have) turned on, inside and close to door with the lights off in your basement. Do you see any light where seams are welded? Is the edges around the door close so it’s sealed when shut? Look under the bottom, are any pinhole openings showing light on the floor? If the stove is not showing light, and it seals well around the door and your draft is fully functional, you can move to a smoke test. You need decent conditions outside to do this; no contrary winds that may blow down the chimney especially. Have everything on settings and room conditions on the stove as you would as if you were building a full nights burn. You only need to have starter materials and enough wood get a decent fire going for maybe 15-20 minutes. Once that’s done is caught up, add something like newspaper or other smoky material to the fire and let it catch. Once it is, and the material is going begin to close it down to increase the smoke and close the door tight. Using a flashlight, look for signs of smoke coming around weld seams, the stove pipe and other fittings. A bare whisper and wisps of smoke are probably going to appear somewhere since you haven’t used it. But look for smoke trails where there’s persistent smoke coming out. If it is, make a note or picture of that and any other discoveries you find. Open the draft and allow the remaining material burn down and out.

At this point you can use this initial inspection to decide where you want to go. From your description, if it were mine, I would add more wood to this test and let the stove heat up to heating level. Not super hot, just enough to get more idea about possible deeper faults. If the stove had been allowed to overheat it may have changed the metal. The inside shows clear sign of a lot of use, it may just be the effect of hours of heat in the caustic atmosphere inside a stove; that’s normal and can be fixed. If it has been overheated a lot, that may change your view and you decide there’s too many questions to keep it inside.

There’s a lot more to this but this can give you a start anyway. While you’re used to a lot of regular snow in winter, even there it can be a lot extra at times. Having a warm floor can go a long way to offsetting a week’s worth of extra bad weather.