[dsraven]

check out what you have for starters. if replacing the lower hinge area first make a pattern to copy the original contour. make a center punch mark a designated dimension above the floor on the pillar so you know where the floor is supposed to be when you install the new part. then cut it apart and weld in the new piece(s).
the door adjusts up and down on the hinge pillars and also in and out to match the fenders and door opening. then the hinges adjust the door fore and aft inside the door where they bolt onto the door. there is a write up in classic trucks on how they get the hinges adjusted on a 55-59 chevy truck. maybe check their tech area online.

find out what you have to work with before you start just doing the hinge pillar repair. you don't want any surprises. remove the sheet metal panel that goes vertically just inside the door on the kick panel area. then you can see the inside of the hinge pillars. it's only held with a couple of screws.