Do you mean the bearings usually used on the clutch shaft, with the extended inner race with grub screws through it?
If so, these are known as the 'set screw mounted' bearing type. Yes, they are available through bearing specialists. NSK make a range of them, among others. You'll need to determine the type number, stamped on the edge of the outer race. Or go by the dimensions.
But unless you can get them at trade price, Greenfield may be OK on price, and certainly less mucking around.
You might find
THIS Greenfield drive rebuild thread useful. The ODK online shop can supply the belts and probably the clutch cork facings - there are a couple of different sizes.
