Need ID on Spencer Carbine and reloading info

[Trebor1415]

I just received this Spencer Carbine from an online purchase. The previous owner was a Civ War carbine collector who passed away. His son sold me the carbine. He didn't know much about it except his father's notes indicated "Original Spencer Carbine" and " .52 caliber ".

Based on my internet research I think it's a 1860 Carbine that has not been upgraded with Model 1865 parts or rechambered for 56 -50.  I'm not an expert though (far from it) so let me know what you think. I may be off base.

Barrel is 22" with six grooves.
Maker's mark is Spencer, not Burnside. It was really too faint to get a picture of though.

I'd like to install a centerfire breech block and shoot this and have some questions. I have read several threads here and elsewhere but many of them are old and some of the vendors are out of business or no longer offering specific products, etc., so if I can get current info that would be great

First off: How do I confirm the caliber is 56 - 56?

What do I need in terms of dies and molds? Is anyone making brass that works in original guns as opposed to repro guns?

Thanks for any help.