Need help please major question

Ok i have been building a new motor for my 90 ls i got a new block, head, etc. Been puttin it together at a machine shop and was about done. Started to put the head together, got the rocker arms and cams in and was about to put my cam caps on and the man told me i could not use my old ones off my old head. He said that every heads is different that they are made for only one head but wouldn't that mean the cams would have to be special made to and i know there not. So can i use the old cam caps on my new head? i would greatly appreciate any feedback on this im desperate to get this done before it gets cold. Thanks