When I first started up my 261 after a rebuild, I did remove the distributor, used my electric drill (not cordless) and removed the valve cover. Ran the drill until I saw oil coming out onto the rocker arm assembly. Let this run for a few minutes to fully prime the oil pump and verified that I had good oil pressure at the dash gauge. After that, reinstalled the valve cover and started it up. Had a new cam so I did the recommended cam break-in procedure. Also used Valvoline straight 30 wt oil which has a good amount of zinc in it and added a pint of EOS oil supplement for good measure.
