104 octane for my 360 ?

Unless you are running boost, the best power should be made with the lowest octane possible. Higher octane slows and cools the burn and in cases where the engine doesn't need it, and it's well tuned, race gas is a waste of money. You have fairly low static ratio (in the 9s) and iron big chamber heads. The only time I noticed a change was when I used C16 (all I could get my hands on) in a jetted lean N/A 440 that needed to run C12. It picked up 2mph just from the fuel...lol.