A reman engine should be just as good as new but no, you can't buy a new engine or trans from Volvo and if you could, it'd be alot more expensive. I believe that they're rebuilt by a place in the US but the name and location of that place is unknown to me.
The engine is just that, a complete engine BUT w/o any bolt-ons like accessories (serp belt, alternator, PS pump, brackets, starter, starter ring gear (flexplate), dist cap, rotor, wires) BUT does come with new spark plugs and a new timing belt.