Mopar LA small block 318 ignition problem

Hello everyone,

I'm new to the forum and I am currently restoring a 1974 dodge dart swinger. I removed the engine a couple months ago to clean, rebuild. etc. The engine is currently installed and everything is hooked up the way it was before I removed the engine. The problem that Im having is that when I turn the key the engine fires, when I let go to the ignition, the engine dies. I already replaced the ignition switch in the column so that's no longer the issue. The ballast resistor isn't a problem due to that I have a msd 6A cal box installed. I'm stumped and really need some answers or at least a path for me to follow. Thanks for the help!