Tap an oil pressure gauge into the port beside the distributor and spin the pump CW until pressure shows on the gauge. Rotate the engine with the starter while you're spinning the pump. Some early 283's need the distributor housing in place to keep oil from dumping right back into the pan, as the housing completes the oil passage to one bank of lifters. I use an old distributor with the teeth ground off the drive gear as a pump-spinning device.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!