To refigure the capacity, you take the known machine capacity x known load center and divide that by new load center. For example:
5,000# machine @ 24" load center. You want to know if your machine can handle a 3,000# load that is 72" long.
5000 times 24 divided by 36 (your new load center) = 3,333. Your machine can handle 3,333# @ 36" load center.