How to match F96 T12 bulbs with a ballast
You have the wrong ballast. The 240 in the product number indicates it only serves up to 2-40W lamps. You probably need a GE 2620S-MV-N. If you can find one.

There has been an attempt to phase out the use of Type T12 lamps which are old technology. You might want to rethink using the T12 F96 lamps for a newer Type T8 lamp or install LED lamps, both much more efficient.  

The energy savings are substantial, at least 33%. So the payback on the original cost of material can be made with 1-2 years of use. 

Just something to consider.

Good Luck