I wouldn't stress too much about this. I spoke to a woman at the Road Home booth at the home show on Sunday. She was the person several others deferred to and stated she was involved in the policy writing. I'm sure it will change again, but according to her, pre-storm value will be determined during the home visit by the assessor based on various factors, including:
1. appraisal within the past 2 years, which will be adjusted based upon how old it is
2. comparison of your property to seemingly equal sales that occurred prior to the storm.
This determined pre-storm value includes lot and land. If considered completely destroyed, the pre-storm value will be compared to the 'repair/replace cost', which is square footage X $130.00.
The lower of the two numbers is the one that will be used. All structural insurance proceeds and structural FEMA funds are deducted from that lower number, which 'should be' your grant.
Of note, you will also reportedly be eligible for elevation funds, including that above 30K received as ICC through the NFIP. Furthermore, you can apply for 7500 for non-elevation mitigation measures, e.g. raising A/C, washer/dryer, adding hurricane shutters, adding house straps. Both this additional elevation and non-elevation mitigation measures are by reimbursement only, meaning you put the money out first and then get reimbursed based upon receipts.
Good luck!