So is the standard set up an AC bearing at the bottom and then 2 deep groove at the top? sounds a bit strange. for 2 bearings at the top I would expect a roller bearing at the bottom (radial loads) and then 2 opposing AC bearings at the top (axial loads).

I know what you mean about getting it working to then build the upgrade parts. Sounds like we are doing very similar projects. I think I will watch your progress and learn from your mistakes.