I love the old GM full size vans. I have an 2005 Safari. Just thinking The shape isn't too far off, haven't looked up the dimensions of the vans yet. Kind of a mix of old and new.
Change the grill, front and rear bumper, add the side markers and 1970 C10 taillights. I know anything is possible, been looking at Lee7673's work, but how hard would it be.