More Power Valve Questions

[SofaKing]

My stock 21 stud engine is incredibly hard to start and runs very rough when it does, will not idle and accelerates poorly. Plugs are sooty black,strong gas smell in cab. I can find no fault in ignition system. I have a holley carb, #91-99. I put a daytona carb kit in it. The Daytona power valve is stamped 5.5 and will drain the float bowl when it is not running or carb is on the bench. Books indicate valve is statically open and pulled closed by vacuum.

I have a hard time believing the float bowl is supposed to drain everytime the car is turned -off. Since the truck has never run before and does not now I also cannot take vacuum readings to select the proper power valve. Lastly, different sources state the "stock" power valve ranges from a 5.5 to a 7.5 and that being off by .5 is detrimental. The carb originally had a #3 stamped on its power valve when I replaced it. I am at 4500' now, truck spent previous life in S. Utah at a slightly lower altitude I believe.

So my questions are:
1. Is the power valve supposed to pass fuel when no vacuum is available?
2. What size is standard from factory?
3. How does one make selection if engine doesn't run/idle?
4. How do you test/ measure the valve operation on the bench?

Thanks