Check Jim Carters for panels. If they don't have any look up Ray Stanley and find out what he has available. He calls himself Wheelrightrest or something like that on everyone's favorite auction site. He makes and sells the only panel/Suburban specific repair panels I'm aware of.
The track width on the '73 4x4 is a bit wide compared to your '49. If you are lifting it you might be fine, but at a stock height you may have tire/fender interference.
Big block and TH350 in a 4x4? You must not be planning to abuse it...
