Sorry if I was unclear, but my question is:
is it possible to replace the valve guides without removing the head, and is there anything wrong with doing this to stop oil usage, as long as compression is good?

A local shop says they can do this for approximately $300, which I can find quicker than the $1800 or so for a valve job. But when I ask other shops about my oil loss they only offer a full valve job. So I must wonder if replacing valve guides without removing the head is ineffective, or inadvisable for some other reason.