A valve seal only restricts oil from running down from the top of the cylinder head, and onto the face of the valve, and into the cylinder, it has nothing to do with compression in the cylinder.
Sounds like your rings are completely done, or you have a burnt/sticking valve.
smokes alot, blows oil but has 15k on it this way so far
can still pull a boat, do a burn out on 35's, and 80 on the highway, with a disconntected fuel injector