There have been a couple of threads about 2C crank rebuilds in the last few days. I picked up my latest rebuilt crank from the engineer yesterday and asked about the big end bearings.
He used bearings from PROX International in the Netherlands (they have a website). The part number is 22.182415. The package is marked " SILVER/15 needle DIM 18x24x15mm".
I believe these also fit some Hondas and KTMs.
The small end bearings might be available from the same people but I had a couple of new Kawasaki items which fit (maybe KH100?) so we didn't buy them this time. I'll look for the packet of those and post the details.