Put your boot on the end of a table. Drop the heel off the table until the sole is resting on the back end of the ball of foot area. Measure the amount of the heel that is off the table and that's how low your heel can be cut down without lowering the heel too much. the boot needs to stay balanced with the heel to be wearable. As for as replacing the block with a lower heel block, it can be done but still has to set correctly. Cutting down a heel block even a 1/4 inch will take a lot of pressure off the ball of foot.
Randy, Thank you for the information! Could someone actually cut the existing heel or would I have to have the heel completely replaced? How much do you think something like this would cost for both boots?