To put it in perspective........ if you run the external lines on the Indy heads to feed a set of needle bearing rockers(like Harland Sharps), and you go from the unrestricted fittings that have the smallest portion of the internal passages at .120” diameter, and put one .060” restrictor in each side, the oil pressure in the motor goes up about 10psi.
Even with the .060” restrictor in place, when I prime a motor with Indy heads and the external lines there is a ton of oil coming to the top end.

Greg has 4 times as many .060” sized feed holes going to the top end as what I normally use.