2800 lb super stock spring question

ordered a set of super stock springs (2800 lb) from summit (p4120863/864). Going on a relatively stock 70 340-4 speed swinger. Car weighs around 3100 pounds- will this be an issue, will I have to return them for the 3200 lb springs?? Also tech said that the spring shackle has to be moved forward as the spring is shorter-is this true. Not a big deal more worried about the weight issue. Thanks for the input!!