Sleeve 22104-ME30-0000 is also the part number for gasgas.
Not able to find a 25x28x26.
25x29x13 is easily found but as you say the clutch drum might be to small?
Bronze bush would need more clearance than the needle bearing though, so might fit?
Hope mine hangs on in there.
I ordered 2 pcs 25x29x13 needle bearings so we will find out soon.