If you are really turning at 6000 to 12000 RPM then with a 50mm offset the system is going to be out of balance and would destroy itself . I question the RPM because you state that you were using a washer motor and were turning it at 14000 RPM. This is not possible, the washer motor would explode at that speed. 1400 RPM would be about correct for washer motor running at 50Hz. Even running in the range of 600 to 1200 RPM, the system is going to have to be somewhat balanced to compensate for the 50mm offset.
The pillow block bearing setup would work OK for RPM ranges of 600 to 1200.