Depending on what crate hemi you have, some of them are known for valve seal problems, others have piston ring issues. One i owned had a leaking rear main seal, along with the leaking valve seals (not too bad). Thats more than likely the source of your oil burning problem, not oil getting past the spark plug threads.
The only time I saw oil get into the combustion chambers thru the spark plugs was when i changed the plugs. It would fire up and smoke pretty good for 10-20 seconds until the oil that had leaked into the combustion chamber burnt off. Thats a typical hemi problem in all of em.
