I'm not saying that there is anything wrong with trying to open everything up so the gas flows as freely as possible.
what i am saying is that no matter whet you do, the volume of gas that will flow will always be limited by the size of the gas line.
even if your gas flow is a trickle, it would still be enough to keep the fuel line and filter full enough to fill the float bowl. once the fuel line qand filter are full, there is enough gas there to keep the float bowl topped off. as soon as ther float drops and opens the needle and seat, a trickle of gas will be enoiugh to re-fill what little fuel was drained from the line into the float bowl.
The object isn't to get gas into the float bowl quickly, it's to get the correct volume of gas into the line and filter to keep the bowl full.
What i meant by the 3" hose to 1/4" hose is that if you have a nice big free flowing 3 inch hose (assume this is the gas tank petcock) and then you stick a 1/4 " hose on it the flow will be greaty reduced.
so, if you open everything up and make it flow as freely as possible, the small diameter fuel line will only be able to flow so much fuel.
I guess what i'm trying to say is that fuel flow may not be as important as fuel volume. since the fuel in the line does not flow all the time (again, the on & off effect) it's more important to be able to keep the line and the filter full of fuel than it is to try and increase the amount of flow. again, the fuel volume is still limited by the size of the petcock opening. so even if you get the petcock all opened up, burrs removed and all that, the flow will still be restricted due to the size of the outlet where the fuel line goes.
And then there is the inlet on the carb., which is small too, so it will cause another restriction in flow because of it's small size.
even if you do increase the flow (for example) from 1 gallon per minute to 3 gallons per minute, the float will close the needle & seat, causing all fuel flow to stop once the float bowl is full.
You need to think of the fuel system as a strobe light and not a garden hose.
With a strobe light you can increase and decrease the strobes(the amount of time that the light goes on and off) with a potentiometer. doing this will speed up or slow down the strobes, but it will not make the light brighter. It will lengthen or shorten the amount of time that the light is on and off. I'm using this example to show that you can increase the volume, and not increase the flow because of restrictions.
think of the volume in this case as the time that the light is on or off, and think of the flow as the brightness of the light. the "flow" is limited by the amount of power that the light uses. the volume can be increased or decreased by creating more or less resistance.
Maybe i'm misunderstanding what you are trying to achieve?
Am i going into this too far?...lol