Re: holes for the rest of the bed.
The rest of my truck bed molding holes would not be the same. I believe it's only the tailight holes and maybe the tailgate that are going to be similar. They made some changes on the side molding after '68.
On mine the side molding follows the contour of the wheel well like the one pictured below.
http://www.lmctruck.com/features/cb/cbml5.htm