Oil pressure relief valve shims (2008)

I was recently working on a very nice MK2A brought in for a basketful of small problems. While tring to sync the dual Amals I left the cap off the oil tank to watch the oil flow. It looked feeble at idle so I was keeping an eye on it. adter a few minutes it dropped to almost nil for the return. So I put on an oil pressure guage and it read 20 pounds. one trip around the block and it was 8 pounds. So I gave the owner the sad news and now begins the investigation part such as seeing if the rocker spindles are in the right position.

seattle##
Make sure the cone shaped seal at the oil pump and timing cover didn't let go. That is where I would check first.
Cheers,
Thomas