I recommend using half the bag and then doing a pH test about a week after application.
I am not sure liming deep is a good idea, the lime is going to sink in over time and you may turn your deep soil alkaline if you use half deep and half on top.
You
should be able to get a decent pH meter at a nursery for under 50 dollars (U.S.) To test different depths, just take samples in glass jars and use the meter to check the samples pH.
Remember that plants will tend to alter soil pH so that it becomes closer to what they desire for their
roots.
Because of the effects of other amendments you may be planning on using, it is a good idea to gather the overall change affect slowly. You can always add more lime, it is a lot harder to get an overdose out of the soil.