The following was borrowed from the Second Chance Garage website and although it talks about restoration the philosophy also carries over to building street rods.
"Purists will say that a car should be restored to exactly what it was when it left the factory, including exterior and interior colors, options, etc. True, cars that are shown for national ranking awards do have the highest value (museums and high-end collectors want them absolutely original) but the real world is very different. When your car was produced it was offered with many options and colors to appeal to the greatest diversity of tastes. When you restore the car, build it as you would have ordered it from the factory in the first place. Choose the colors and options you would have wanted back then. The finished car should please you, not the next buyer. Sure, the car won't be worth quite as much money at selling time but the enjoyment you got out of it will more than make up for the difference. In the minds of most restorers there is nothing more pathetic than a flawlessly-restored "trailer queen" that is dragged from one show to another and never started or driven. Automobiles were meant to be used and unless yours is the last, document example of a particular car in existence, restore it to your tastes."
When building a street rod or muscle car for your personal enjoyment, do it your way. Build it for you, not the other guys. If you follow this philosophy you will be much happier with the final product.
One final thought: Be an individual. There's nothing more boring than another "cookie cutter" small block Chevy powered street rod. Put a Ford in a Ford, don't be afraid to run a Flathead, find an old Caddy motor (they have plenty of power potential), seriously consider a Buick Nailhead, or put a Hemi in that thing. Anyone can build a small block Chevy, but it takes a real "car guy" to build something a little different.
Most of all.... Enjoy the hobby.