The Mityvac or similiar has hoses & fitting, plus a small plastic bottle, several ounces,(reservoir) with it . One outlet of the lid for bottle should be marked to pump and the other outlet goes to source. This is used to draw brake fluid, gas, etc. and to isolate from pump. I used a cone shaped fitting on the end of plastic hose the apprpriate size to fit snugly in gas line. It is easier to attach this fitting into rubber gas line on top of engine between fuel pump and carb. You are trying to draw fuel from gas tank through your fuel line and fuel pump up to that point. You may not be able to draw through fuel pump though. Next step would be to disconnect rubber line between hard steel line running from rear to front of car. Right where it attaches to inlet fitting of fuel pump. Try to draw gas into plastic bottle again, you will not see much vacuum with bottle attached. Keep squeezing pump until gas enters bottle. When you see an ounce or so of gas, STOP. Respect the gas. Be ready to disconnect vacuum pump from fuel line and reconnect line to fuel pump. As stated in another post you can clamp rubber line full of fuel with vise grips. If you can not draw fuel with vacuum pump , this is why fuel pump is not working. Since you said you blew out steel line, you can rule that out. Next easiest thing to check would be rubber fuel line between fuel tank and steel line in the rear. If hose is split or not clamped correctly, pump will not draw fuel. Steel line to front has a ridge around it and rubber line should extend over it and be clamped behind it. Sometimes rubber lines can seem to be installed right when they are not. Especially when they are in hard to reach spots.

On a car that was previously running, this would show up as a gas leak. But, on a fresh restoration this is just a vacuum leak, preventing fuel pump from drawing gas. Last resort without dropping gas tank, is to attach hand vacuum pump to rubber gas line right outside of gas tank and see if you can draw fuel from tank.

Once again I hope this helps and I am not leading you down the wrong path !
I know it is painful to get that far and not have your Bird running.
I wish I was nearby to help in person

Jeff