Say you have a 10.5 cr engine. Most stock 1st gen's.
Take to the track with 93 octane, see how it runs.
Then add 110 to the 93 without changing anything else. About 50/50.
Bet you find it likes 98 the best all things considered.
This will be very close IF the engine, gearing and outside air is ideal.
Know it's hard to get ideal on all catagories, but a 10.75 DOES NOT need 110.
From 75 thru 83, i never went faster with my RAIII using anything higher then 98.
400 with 69cc #12 heads, stock 744 cam.