If you remove one of the gas lines from a carb and blow into it, do you hear the air coming out in the tank? That will tell you if there's a plugged line. Some AC sleds had gas shut offs between the fuel tank and the fuel pump, so look for that as an issue.
If you hear air but no bubbles, it could be the pick up tube inside of the tank has fallen off. The hole in the tank is not on the bottom, so if the line falls off and the fuel level is below the hole, no gas will make it to the fuel pump. Sometimes you can look in the tank with a small light and can see the fuel line.
Once you have made sure the system is intact from the metal filter on the end of the pickup tube, through the bulkhead through the shut off, and through the fuel filter, with the carb end of the fuel line in a container, pull the rope a few times. Are you getting any fuel? If no fuel, it's possible that the fuel pump needs to be rebuilt or replaced or that the impulse line from the crankcase to the fuel pump has cracks in it and cannot send an impulse to the fuel pump diaphragm.
If you do get fuel, are the carb bowls getting any? If not, the inlet needles are stuck in the seat. A good cleaning will often solve that issue.
That's a few things to check... good luck!