416 low oil pressure at idle
Its the Lunati bar bell lifters that are the cause. With the high lift cam the oil band is dropping out the bottom of the lifter bore. I just went thru this on the 600hp 408 I posted a few days ago. I caught it during mock-up. This will cause the low oil pressure issue. I have call Lunati and pleaded to them to change the lifters of put in their description that they are not for high lift applications.
Its not the bearings or the filter, Its the Lifters. If you want to solve it, change them out for the Howards EDM's and it will not have low oil pressure any more.