Information ans spare parts

[Pete Holland]

Hi all,
I joined the Cas recently after acquiring a battered and incomplete Spencer carbine M 1865 with serial number 21512 from a British auction.
Home country: the Netherlands. I would really appreciate your expertise and comments onthe following questions:
1, the carbine was sold as a 56-56 with .52 rimfire caliber. I read elsewhere that the M 1865 productions were in .50 caliber. Can anyone tell me which is the right caliber?
2. As mentioned above: there are numerous parts missing. If I buy an ectractor, extractor spring, ectractor screw and other parts which correct desfription should I look for? Are the parts for the 1860 model and the M 1865 the same?
3. Ultimately a centrefire block would have to be fitted. Do all the "old parts" function the same with the centrefire block?
4. I have tried S&S, Ols Arms of Idaho Buffalo Arms and most of the sellers on Ebay. None of them are willing to ship to the Netherlands making restoration fairly difficult. Can anyone offer suggestions on how we could overcome this issue? Are there other spare parts companies I could contact?

Apologies for the lengthy post but I hope to get some input from experienced members.
Thanks in advance and regards,
Pete Holland