Dave,
Welcome abord and thanks for posting!
As you read, post,and get to know guys who collect and shoot these beautys, they can pass such information on to you.
Often dealers on the Gun Auction sites deal in them and in some cases rifles come from auctions in Europe (through "contacts" who speak the languages) I bought my beloved HW-55S through a guy, who knows a guy, who deals through German Auction and Estate sales. Many times it is MUCH more simple!
I will refer this post to a friend who is better versed in just how to find the older Match guns.
ZVP (KI6FNN)