I don't see why not.
Lead was removed from gasoline due to emissions- both as a contaminant and because it fouled the catalytic converters- neither of those is an issue.
As for the octane, do not expect better performance. Ironically, the higher you altitude, the lower the atmospheric pressure and the less likely an engine is to detonate. This means lower octane can safely be run as higher elevations.
However, because you will not be increasing your compression ratio (I assume) the increased octane will not help- what race gas or even aviation fuel allow (because of higher octane) is a higher cylinder pressures and the ability to advance the timing without fear of detonation. You engine was designed for standard octane and will not detonate on it. Add to that the lower atmospheric pressure and detonation is probably not even possible. The only way to realize any benefit from the higher octane is to increase cyliner pressures with an increased compression ratio or forced induction.
You may even run into problems running the higher octane gas, not because of lead, but because it may not ignite as readily as lower octane, especially at higher elevations- but that is the entire purpose of higher octane.
If it were me, I'd save the fancy stuff for an engine that could use it.