Need to know why car wont start,

Check your ground wires next.

Things should be tested before you buy parts you don't need . Shooting from the hip is not how to solve auto problems . Cool car though , I had one years ago .

Any of the causes listed may be your problem. As beatupchevy said, Do your testing first and you will save from unnecessary parts purchases. Could also be the alternator or ignition points or condenser. I, too, had one back in 1971 (also a '66, and '73).

Relocate the negative battery cable from the exhaust manifold to the power steering pump mounting bolt. The exhaust manifold was a terrible spot to mount the cable. I did this on my 70 Catalina. Hope that helps! Jim

Oh yeah , the condenser under the distributor cap , I had to do mine years ago . Who would have thunk .