You get what you pay for. A cheap reman engine might be ok, if they started with worn rather than damaged components. Some production line reman shops do everything in bulk, mix and match as necessary to crank out as many as possible others rebuild one at a time. I've seen some that come out OK and are useable for your grocery-getter or everyday light use vehicle. I've seen others as described above. One I took apart had the valves ground so far that they had a sharp knife edge around the face! but burning one never came into play, the bottom end puked out the bottom of the oil pan before it could burn a valve.
I would trust a Factory Reman engine, a one at a time rebuilder or myself, but I wouldn't spend my hard earned frogskins on a cheap high volume production shop. For a SBC, a "Goodwrench" replacement engine is not too expensive, and is backed by GM. Variations are available from wimpy to killer depending upon how much you need. Any GM dealer can hook you up.