I believe obtaining the correct case is the answer and to this end I have located and purchased a 30T2 SC PC which I hope is winging its way to me from Austria as we speak, As to the Donor movements I findd I have a Choice of two both have been in my little cppboard for quite a while, both were servced. Below are the pair.Photos fresh off the Z6.
New case is a 2056-1

 

Do either of these movements come with a correct case?

 

Both these movements are caseless, the correct case for the movement which started this thread is a 2056-1 which I located in Austria and purchased.