64 Dart 273 Engine Vacuum

Sounds like you flooded it.
If you have done this several times, the gas ends up on top of the piston and during cranking gets onto the cylinder walls where it washes off the oil, and eventually most of it gets into the oil, with some of it going into the exhaust system..
With the oil washed off the cylinders, the ring-seal goes away, compression falls, and starting gets harder.
When it finally does start, the hot and flaming exhaust can ignite what is in the pipes and mufflers making an awful noise.
The usual cure for this is to remove all the plugs, disable the coil, and pump the gas out. After that I squirt some oil into each cylinder and slam the plugs in a few turns, then again, crank the engine to distribute the oil. Then pull and clean the plugs. Next put the plugs back in and now she's got some compression!
Sometimes, if you have really flooded her, you might want to change the gassified oil.