With a completely empty fuel system, I fill the tank at least 1/4 of the way, use a MightyVac to pull gas up to the fuel pump (or blow a bit of air in the fuel tank), and fill the carb float bowl(s). Assuming you have a good fuel pump, it will start and run just fine without it dying on you.
Should have done that with my 273 but I assembly lubed the heck out of it and pre-lubed the oiling system. With a Magnum starter and a fresh battery it spun over plenty long but was ok when it lit.
