CWs Spitfire rocker oil pressure video

My 79 Triumph Spitfire rocker assembly has low oil flow, with the engine up to temperature, 160F, and 40 PSI at 900 RPM. I noticed inside the valve cover, the rocker was looking dry, so this is what I found, (the video). The oil flows from the rear main oil passage, through the camshaft rear journal, up to the rocker shaft. The cam's journal has 2 flat areas, one is 90 deg to the other one, to allow the oil into the rocker assembly oil passage. A hole in the rockers lubricate the valve adjusters and run down the push rods into the cam followers. The rockers also have a small hole on top to help lube themselves and the shaft. My cold engine was making 86 psi oil pressure at 3000 rpm, and 40 psi oil pressure at 900 rpm. The pressure is lower when the engine is at 160 deg. I am using 10-30 weight oil for cold weather driving. A modification I made last year was I enlarged the center main oil passage to 5/16" during this rebuild. Has that reduced the oil flow to the rocker ? I don't know yet.. Further investigation needed. Edit 29 Feb 2016: I'm told "These engines have a low oil flow to the rocker, that they seem to need more but oil mist and some splashing from below does the job".... Well further investigation, I checked the oil pressure at the rear main with another pressure gauge, and found a 10 pound drop in pressure after the center main. Gauges were changed to see if one was different, they are good. Xtra oil feed line is an option, but has problems of it's own, need a restrictor so not to flood the rockers, and starve the rear main. Changed to 20/50 VR1, spring weather is here, warm weather needs heavier oil. On a warm afternoon, and interstate speeds the oil collects heat, and thins more. I saw a low 20psi when I stopped for a engine check, the rear gauge read 10 psi (800rpm). Oil pressure picked up as rpm picked up.. Open rocker running engine oil video Feb 2018, the running oil pressure is much more oil to the rocker in that video.