Question about replacing t12 to t8 fluorescent tubular lamps.?

It will probably be cheaper to purchase a new fixture than just replacing the ballast. Price out both options. Eventually you will no longer be able to buy the T12 lamps..but you are looking years down the road. T12 bulbs are typically magnetic, and T8 are electronic. The T8 don't have the humming noise that you can sometimes hear from a T12 fixture. Like I said, price out both options but more than likely it will be easier and cheaper just to purchase a new fixture that will use the T8 bulbs.