Getting the 69 C20 to run after sitting

[Gruman]

After sitting for 7 years, I got the truck running and hauled back to my place. Have had it running a few times since then just fine. (it would start and idle great) Now it wont start. I believe the 350 motor is from a later truck, 78 to 81~ish with a 4 barrel Quadrajet on top. (OE I'm guessing) Everything pretty much stock.

Here's the problem: It wont start and run. I can pour gas down the carb and it will run until it uses up the gas. I've got fuel to the carb, (fuel pump works) checked the fuel filter (clean) but just cant get it to stay alive after priming it with gas. Fuel line has plenty of pressure, but its like its not getting through the carb.

I'm pretty fresh with carbs so anyone have any suggestion on where to start?