1977 Chevy Truck NO FUEL?

I'VE GOT A GOODWRENCH 454 IN MY TRUCK. THE OTHER DAY FUEL WAS LEAKING FROM THE FUEL PUMP, I TIGHTENED THE SUPPLY LINE TO THE PUMP BUT IT STILL LEAKED. YESTERDAY I REPLACED THE FUEL LINE. I BACKED OUT OF THE DRIVEWAY AND THE TRUCK DIED. IT HASN'T RUN SINCE.
AFTER LOOKING AT IT A WHILE I COULD SEE NO FUEL WAS BEING PUMPED. I BOUGHT AND INSTALLED A FUEL PUMP. NO CHANGE.
TRUCK RUNS WHEN THE CARBURATOR IS SUPPLIED FUEL.
WE PUSHED THE PIN BACK INTO POSITION (I ASSUME) ABOVE THE ARM ON THE FUEL PUMP DURING THE INSTALLATION PROCESS.
NO VACCUUM IS FELT ON THE SUPPLY SIDE OF THE PUMP WITH THE ENGINE TURNING OVER.
I BLEW BACK THROUGH THE SUPPLY LINE A FEW TIMES, LISTENING TO THE TANK BUBBLE. WHEN I STOPPED, FUEL WAS PRESENT IN THE LINE COMING TO THE FUEL PUMP.

SO, THE QUESTIONS I HAVE ARE AS FOLLOWS:

1) IS IT POSSIBLE TO ASSEMBLE THE FUEL PUMP AND MISS THE PUSH ROD? WE ONLY HAD ABOUT A 1/4" GAP THAT HAD TO BE CLOSED UP WITH THE MOUNTING SCREWS ON THE PUMP, I ASSUMED DUE TO SPRING PRESSURE ON THE ARM OF THE PUMP.
2) HOW IS THE PUSHROD ACTIVATED IN THIS MOTOR? DOES IT RUN OFF A CAM LOBE OR IS IT A ROCKER ARM ASSY OFF THE CAM?
3) COULD ANYTHING ELSE BE CAUSING THIS? MY ASSUMPTION IS THE PUMP SHOULD GENERATE SOME SORT OF MINOR VACUUM ON MY FINGER ON THE SUPPLY SIDE OF THE PUMP IF IT IS WORKING CORRECTLY.

THANKS! CAN'T GET TO WORK TOMORROW WITHOUT IT.