Is 9.7:1 compression on iron heads too much for 91 octane

Just for some perspective, first full engine I built from the block up was a 360 with Magnum heads and KB flat tops. Static CR came out to 10.42:1. It should have ran fine but it pinged like crazy in warm weather on 91-octane; problem was I was stupid and reused the small Voodoo cam I had in a previous 318. The 256/262 adv. duration version that's intended to boost cylinder pressure in smaller low-compression engines, the OPPOSITE of what I needed. However even with all the pinging it still lasted about 25,000 miles and I beat the hell out of it, made maybe 9 passes down the drag strip and lots of screwing around in "Mexico".

If I had simply changed the camshaft for one that was designed for my engine combo I'm confident I could have stopped the pinging and that engine would still be running today. Live and learn...

Now I'm running a stock junkyard 5.9L Magnum short block (stock pistons etc.) with open-chamber Edelbrocks so my static compression is just about 9.0:1. It has noticeably less bottom-end grunt than my 10.5:1 engine but still a lot more than I expected (it has no problem pushing my Duster from a dead stop with 2.94 gears and a cheapo 2600-rpm stall converter). This time I went all the way and called Jim at Racer Brown for a custom-ground hydraulic roller cam for my exact setup. It runs like a champ, screams to 6000+ RPM and has great street manners, also runs fine on regular pump gas (85-octane here at high altitude) which is a nice bonus. The best part is the heads came with ARP head studs which I installed with Cometic MLS head gaskets so whenever I feel like it it's ready to take some boost.