Ditto what AndyF said; there are more differences every year '62-'65 than a casual glance shows. He helped me on ft hanger info on my '64, which is #AR0097. '62-'63 used the shorter 20" ft segments that A-bodies use. '64 (& probably '65) used the 21" front segment springs. Rear axle width differs between some model years, too. 285/70-15s on an 8x15 4.5BS wheel will rub up in the wheelhouse if you don't get the axle width right, and you gotta watch the lower ft corners of the front wheel openings if you go big/tall/wide in front or use a disc brake kit that widens the track.
A tape measure & some mock-up time will save you a lot of grief building an early-B.