Jim,
The stem seals I have used slipped all the way down the valve stem, clear to the top of the valve guide. When the engine is started, the travel of the valve will set the final location of the seal.
We called these "Ford" type seals. They wear a relatively soft plastic umbrella style that merely pushed over the valve stem before installing spring, retainer and keepers. They travel up and down with the movement of the valve.
I don't remember ever seeing a stamped steel shroud around the valve spring on a Chevrolet six. I have seen them on the V-8's though.
Stuart
