The actual bearing doesn't seem like it's available anywhere, OGTS doesn't even list one for the 7007 donut they sell.
Pretty sweet That the Opel bearing actually fit the Chevette Shaft though. I wasn't expecting that... If a person could get their hands on some Opel GT stuff. they could probably use the torque tube bridge complete with the larger donut and have an available bearing. If only I could get my hands on one of those, my setup would be completely rebuildable