Cly-head valves ?

My machine-shop has told me I need ALL new valves.  The machinist actually working on my head and cyl's wasn't in to work yet when I talked to the shop foreman so I have yet to learn why my valves need replacing. 
Several exhaustive searches for replacement valves has proven to be challenging.
I have had one reply from Germany and am waiting on a more definitive answer from them.  My concern at this moment is regarding a possible difference between the "Z", "ZN' and KZ valve design and specs.  I came across a comment "somewhere" that there is a difference. 
Obviously I don't want the machine shop to tell me my NEW valves are incorrect, so am hoping for an independent answer from someone who can qualify this.
Thanks

Not much help but Partzilla shows ZN1300 intake and exhaust valves only fitting ZN motors (83 to 88).  Doesn't mean they wouldn't fit but they could be too long, or too short or different diameter stem/tulip.

I believe the ZN and ZG models had larger diameter stems compared to the KZ / Z models.    I was trying to find Dave Ewing's write-up concerning all the changes to the 1300 throughout its production life, but no luck.

ZN valve stems are larger diameter than KZ or Z valve stems.  David Ewing suggested the possibility of replacing the valve guides with ZN guides, but had never actually tried it.  Maybe the KZ valve guides could be reamed to the correct diameter to fit ZN valves? Wish I could be of more help.

It took some time and correspondence but I was able to find a supplier (Australia) for new Vesrah valves.  Prices were very competitive and I got a break on the shipping. 
Details to follow when they arrive.
Thanks to those who tried to help !
 

Positive verification new valves are *really" needed from shop tech?