just get a double depth banjo bolt the same size as the charger outlet bolt, then run a pipe from the 2nd connection on that to a fuel pressure gauge (or some other type of mechanical pressure gauge) mounted on the dash.
I'm not sure what use this is with the charger still being lubricated from the engine oil though, I only did it when I was using a stand-alone oil system to make sure it was working. If you think one of the oil lines is blocked, disconnect the one from the t-piece on the head and then make sure oil flows out of it when the engine is running.