Your okuma classic is really designed for use when boat fishing, where casting distance is not a top requirement. However, the principle stays the same. The overun occurs because the spindle is spinning faster than the line is coming of the reel. At the beginning of the cast the spindle is traveling at its maximum and matches the speed of the lead pulling the line of the spindle. Towards the end of the cast as the lead slows down the spindle doesn`t. And thats when youy get a birdsnest.

To prevent the overun you will have to slow the spindle down to match the speed the line comes of the spindle. This is done by gently thumbing the spindle at the end of the cast. It takes some practice and at first I think its better to be cautious and thumb (brake) the spindle early. If you want to cast significant distances it would be best to get hold off a multiplier with centrifugal or magnetic braking which helps reduce the chances of overun.

I hope this helps. Any more questions you can always PM me.