Install of interior kit - rip off !

One fault I have seen with do it yourself and some so called profession shops too...
Ignoring the water shields in the side panels. If you replace them as good or better than the originals you will extend the life of the upholstery panel. I replace the original wire clips with newer type sealing clips. So many little details make for addition cost.
What a shop will do or not do isn't a question if you do it all yourself.

The one thing you probably should pay the experienced pro to do is the headliner.
Most recent pic I've seen of a very typical headliner install is a white 67 Barracuda on ebay that was pointed out in a thread here yesterday.
Mine looks only a little better and I've done the job a few times. Enough said