Installing front Door pillar patch panels

[Dodge68charger]

I put a new cab floor in my 68 c10 and now need to replace the front lower door pillars just below where the bottom door hinge mounts. How do i go about replacing this piece. What do i use for reference as the new patch panel does not have the four holes needed to line anything up. I dont want the front rocker to be off and the door not close. Any help would be great
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