Running new flex lines on a 69 Barracuda (location?)

Welcome!
I ran my lines next to the rocker and had no problems with punctures or crushing. It was not an everyday car but did see rainy weather.
If you have frame connectors,I'd run it on the outside of them,holding the clamps on with little tabs welded to the connectors.
Any pictures of your car?

I have my return line inside the frame connector. Wish I`d thot about that when I was originally subframing it , I would have both feed and return in it .