some of the practice books out there have a sort of rubric for scoring in the back, but i can't remember any offhand and can't do you much good because i threw those suckers away the second i got my august scores back. what with the disparity between the number of questions for verbal and the science sections, i think you'd have to do a lot better on the verbal to get a better score now. but yeah, it's curved each time to the people who took it.
there was an interesting debate a while back whether the april or the august mcat had the better curve. you figure more people take it in april, so the curve might be better with more people, but then in august people have had a whole summer to study so they might do better, making the curve worse. but it's hard to change your score, so then again the curve could be more lenient. heck, it's all a crapshoot, so put it out of your head and just study. good luck!