the distributor forms one wall of your oil passages when its in place, if you checked oil pressure with it removed that explains your testing of the rear bearing leakage.
your oil pressure is a measure of the resistance to oil flow rates, you can either increase the oil flow or increase the oil viscosity or decrease the oil leakageread thru these threadsviewtopic.php?f=54&t=615viewtopic.php?f=54&t=52viewtopic.php?f=54&t=525
btw while were talking about weird oil pressure, many guys don,t know that the 1965-early 1966 BBC engines REQUIRE, the rear bearing journal on the cam to be GROOVED or the oil will not flow correctly
If you get the correct cam bearings for the motor 65-66 blocks use Sh615S cam bearings and you must machine the rear cam journal . 3/16 wide by 7/64 deep You can tell 65-66 blocks by them not having a grove in the rear cam housing
396 clevite SH615S 65-66 only(grooved cams)
clevite SH616S 67-93 (non-grooved cams)1967-93 cam bearings don,t require the grooved bearing or grooved cam rear journalhttp://books.google.com/books?id=HfbRYV ... al&f=false