hi,  Make 100% sure you have the proper 2.8 shaft for the motor. If you have the older 2.8 run the numbers on the cam to make sure you don't have the truck cam, they won't fit if not the right one.

New cam = new lifters. even reground cam needs the lifters to be refaced, otherwise you will destroy the new cam. 

When I rebuilt my 2.8 I used stock parts with no problems.  Depends I guess on what your plan is for the build and what you want it to do.  My heads were in good shape so I used the original springs they were in tolerances

hope this helps