I just reread most of the posts on here, I didn't see mentioning to make sure that the factory tin valley cover is sealed up tightly to the heads and intake manifold, not uncommon on B and RB even hemi motors to suck oil into the intake ports from the valley Was there, is there oil in the intake ports I have had many B and RB motors have that issue after blue printing, assemble the motor with the heads torque on and set the intake manifold on the motor WITHOUT the valley pan, use a feeler gauge(smallest one possible to start with and work up to one that won't fit) to see if it will fit in between the heads and intake If it does then write the size down on each corner(top and bottom) of the manifold(so you don't forget )and take it to a good machine shop to have the manifold cut so it fits square on the motor I've seen a tenth and a half or more gain result from sealing the intakes up properly I wonder if the grey oil is from moisture, condensation