that tells me that the intake is setting too far down in to the "V". On dry mockup I would want the bolt holes to be pretty much centered in the intake manifold holes and I would want the head and intake surfaces to be flat & I would not angle milled. thick paper gaskets on either side of the valley pan would be what I would mockup with to see if I can get the bolt holes back aligned & I'm thinking that will take care of the oil consumption. You are working with a "fixed" dimention valley pan which complicates things & I dont have the last word on this (been on SB's for decades) but hopefully this is will help. People have been useing valley pans dry with no issues (as did Ma) but everything has to be dead on for good sealing over time.