The carburetor body is as clean as it's ever going to get, and individual parts have been stripped. I've reinstalled the floats and main jet. Pics of that are below.

Unfortunately, I need new o-rings before I can go any further. I can't find any online at all. A few vintage parts suppliers have carb rebuild kits or gasket kits what have both the o-rings and new gaskets (which would be a bonus) but none of them are in stock. If you know of a source for 64-65 carb gaskets and o-rings, please let me know!