1972 dart 318 problem starting

When it cranks but doesn't start in park, do you have spark or fuel in the carb? When it doesn't start, do you immediately put the car in neutral to start it or has it cranked for a bit? I think verifying you have fuel and spark when it cranks but doesn't fire is the first step.
Have fuel in the carb, has a steady stream of gas from the accelerator pump, have checked that already. As for if it doesn't start in park I usually crank to get the fuel pump moving some gas, then pump it a few times and if it does not start I then try and put it in neutral to see if it will start, most times once put into neutral it will start right up. If the car does not start in neutral I will have someone crank the car in park and take the air cleaner lid off and hold the throttle at almost wot and have them crank and then it will start but will smoke like it is flooded. Carb has been rebuilt within the last 4 to 5 years. I will have to check spark when trying to start it and see if I get any.