I think I'd follow Okuma's specs. Sounds like you could put 150 yds. on there.
One sure fire way to get it right (though it will take a few steps) is to spool it all up reverse of what you will fish with-- i.e.- wf line with the head first (dt line won't matter much which way you spool it), the backing to the outside,tie the backing on (typically use an albright knot.) Spool backing on untill you get it where you want-- (I try not to 'crowd' the edge of the reel). This is where the extra steps come in: un-spool it all, (remember you have the line on the bottom), and respool it with the backing on first.
Does this make any sense? I'm not being very concise today, sorry.