What does the POH say about fuel or in section 2?
Just because it says 80/87 that is not the end of it. The ASTM is an industry standard and in no way reflects a FAA approved fuel. ASTM is irrelevant in terms of its aviation approved status.
FAA have to be dealt with first.
Trust me on that
In fact legally you need only one of the two approvals, and it sure ain't the 4 letter one.