i have primed engines with a pressure tank i built.
i fill the filter when it's installed, then fill the tank with 4-7 quarts of oil, indicated with a sight gauge/tube on the side of the tank.
the fill cap has a tire fill valve with a 1/8npt fitting in the top. i pressurize the tank to 40-45psi.
the bottom of the tank has a hose with a 1/4npt ball valve and adapter[s] that can screw into the oil pressure gauge tap. quick connect hydraulic fittings are used to keep it a no mess operation.
open the valve and "shoot" the oil into the engine, watching the sight gauge go down until the oil is almost gone, then shutting the valve while there is still some oil visible in the gauge tube.
unhook the tank, install the appropriate sending unit, and fire it up.
instant oil pressure.
just like a "home made" accusump system.
this is just my personal experience. your mileage will vary.