A CRO is piped on the outlet of the evap and a metering device would be piped on the inlet side of the evap (for quick check if not sure of what you have). In the pic it looks like you have a cap tube (unless that is your tstat). Seems a little strange to think a cap tube would be sized to overload a compressor on a warm coil but what do I know.
The ABO label would make me say R502. On older stuff I kinda like to avoid POE so I'd use R408a.
Old compressors used a gasket on the sight glass and they can be a bear to get out. Tough enough that you might need to turn the compressor over, remove bottom plate, and punch the glass out from the inside. If it used an o-ring only thing you will need is a drag link socket (like a bit screwdriver bit).