Case 580 super E Brake questions

I'm rebuilding a brake master cylinder for a customers 580 super E. It is the latter model with wet brakes. What oil should i put back in the master cylinder? It appeared to have 68 hydraulic oil in it? Can you get to the slave cylinder from underneath to bleed the brakes, or am i going to have to pull the floor out of the cab? Thanks in advance.

Case 580 super E Brake questions