hard to say how worthwhile the batteries are without more information. Some very large batteries are very worthless, while some are a goldmine. The 1000lbs by itself is not that unusual; with my ten 12v 75 ah batteries I'm looking at adding about 600 lbs. 150 Ah, which is what I would really like (but these were free) would be ~ 850 lbs. So don't worry about that too much; but you should check the GVWR and make sure that you're not too far over. You can anticipate taking something like 300-400 lbs out, depending on the size of the engine. If curb weight - engine weight + battery weight is < GVWR, you're good to go.