I've converted my 82 virago xv920 to a single carb. The gas tank has 2 petcocks. I ran a fuel line from both petcocks to a T line then to a fuel filter and to the single carb. I can get fuel to gravity feed to the filter.
Long tube normal pressure short tube is reserve and will empty the tank, the large hose fitting is your fuel outlet, the small pipe needs a vacuum from the intake manifold to turn the tap on unless you modify it. Little hex head on the bottom is the bowl where dirt and water will collect, thread that off to dump it out any time you need to, or to test the fuel flow from the tap.
sometimes it might look like no fuel is moving and air in the lines with that sort of set up. i see it with the older ducati - pantahs, bevels - a lot. remove the carb float bowl and hold the float up to stop fuel flowing. turn on each tap one at the time, drop the float and see what happens.