Nothing wrong with using leaded race gas.
Advantages: Higer octane resists detonation;
Lead lubricates the valves

Diadvantages: Higher Octane makes less power(yes...but less octane promotes destructive detonation);
Lead promotes corrosion in exhaust systems.

Actually, I use leaded race gas (VP) for a strange reason--almost infinite shelf-life.
Cheers.