This is not for the faint of heart.
Where did you obtain the bearings?
Okuma is VERY particular on bearings. The pick only the best of the best from the manufacturer. Mostly NSK.
Have you ever fit a bearing before? These are questions that need to be asked. Do you have grinding capability once the stack up is calculated and you need to grind the laybrinth?
There were many UPDATES to the ESL-8 spindle. This is why it is highly advised to have an okuma rep rebuild the spindle.