No matter what year 65 to 68, Shelby or not...
the chances of doing damage to any of the paint finishes, chrome finish and the beltline moldings (fuzzies), is really high. Since you are asking this question and the way you asked, seems to suggest you are already frustrated with the processes shared by others.
I get the feeling you may be even more upset if you damaged any of the aforementioned. (I know I would!)
There are times it is wiser to pay for such "risky work".