Help please. 360 off dyno, now won't start in car...

I finally installed after 3 years my newly rebuilt 360 in my 74 dart sport. I had the engine tuned up and on the dyno a few months ago and was running very well. NOW I finally have everything hooked up in the car, while in between the dyno shop and installing it i definitely made sure not to move or change a single thing so it would hopefully start up just fine. Today, that didn't happen at all, when the engine starts it is extremely rough idle to the point it dies, that's if it can even stay idling. If you give gas it might back fire and die. What could be the problem here, I'm at a loss with what it could be. The distributor never moved from the dyno shop and all plug wires are in their locations. Could it be bad gas? The gas in the tank is pretty old. I will say that the carb had to come off to install the motor I'm sure nothing was moved on that either.



Thanks for any help !!

-Aaron