[JQmile]

If you retard your timing enough you can run almost anything on anything. My drag car runs 91 octane with 12:1 compression, but anything over about 20 deg total timing and it will start pinging.....and of course more timing is better for fuel economy. I'd say you're going to be fine with the thinner h/g. I think 10:1 or more is when you'll start needing devices that will pull back timing.