The answer to your question is somewhat akin to asking 100 men what makes a woman attractive............you will get 100 very different answers.

I also grew up in the '50's, and have seen a lot of "custom" cars over those years. Some ranged from very nice to downright ugly, but each one featured modifications that the owner felt were complimentary to the original car. Some customs were stockers with simple modifications like removing (or adding) some chrome, a different wheel (or hubcap) treatment, etc. Some were more radical with things like chopped tops, severe lowering, custom paint, etc.

Your customer will be the one to answer your question. He or she may want you to do some things you feel are not the best way to go, but ultimately, they are the one signing the check. All you can do is offer your best professional advice and try to steer them to something they want and can be proud of. Bottom line however is that you are not building these cars for yourself, so your involvement will be solely that of paid builder.

Good idea to do market research like you are doing though.

Don