You say your ring seal is good. I've ran Hemi's since 1980 and I ran dykes rings on Direct Connection pistons and didn't use a quart in 500 miles. I would suspect those MP heads. I'd pull them in the car and check valve guide clearance, seals and the studs that go into the intake ports. Tim Banning did both sets of Stage V heads for me and it's like magic, no oil consumption.
