Save as much original metal as you can. AMD sheet metal is as good as it gets now days, but even then I would not replace the whole quarter if I didn’t have to.  Other brands like Goodmark are best used for patch panels, IMO.  The new metal doesn’t seem to have the sharp bends of the original.  Look at your new and old metal where it wraps into the door jamb; rounded, not a sharp 90. Also around the gas hole on Challengers, it’s beveled, and not a sharp 90.  Then you are dealing with the 1/4 window, back window and trunk channels... a lot of work.