I'd recommend leaving the head as is and let the machine shop take it apart and examine it. You might want to put some penetrating oil on a shop rag and see how much rust you have, if it wipes off you may have a slim chance of things working. If the rust is deeper and formed pits in the cylinder walls things will never be right. I've found in most cases when a cylinder head is freshened and put on a worn lower end you will really have blow by and in the end have an engine that you are really unhappy with.
