You should add a heat shield also. I like the 100 octane low lead - it’s expensive but you will enjoy the ride.
Afaik it’s ok to mix the different grades. There is also a 114 or so octane that you’re not supposed to pump directly into your car - 5 gallons of that in a 15-20 gallon tank would work. I believe the higher grade fuels are actually better than the everyday gas for engine, gaskets , etc.