I borrowed a spread sheet and changed it around added imperial etc
in New Zealand out 96 octane is the same as your 91....so based on that all my research is showing no more than 8.3:1 on iron heads
which is what my test engine can achieve with a early closing intake....
With cast iron heads on a Small Block Chevy I would not push the Compression static ratio or Dynamic compression ratio unless your using Factory Vortech cast iron heads, GM Fast Burn Cast iron heads that were sold over the parts counter, or a Rare Set of cast iron SBC Dart 18 degree valve inclination heads made for Dirt Track Racing similar to Brodix 18X heads.
I looked at your spreadsheet and I would be satisfied myself with 7.4:1 - 7.7:1 Dynamic compression ratio for 91-93 RM/2 USA inland pump gasoline.
My 1976 Pontiac 455 in my 63 Pontiac Grand Prix has a Static Compression ratio exactly 8.4:1 only and Dynamic compression ratio of 7.7:1 I recall calculated.
It's much more important to match the camshaft duration and LCA lobe centerline and ICA ECA Intake centerline exhaust centerline to the power band of the engine your building.
Retarding ignition timing to avoid detonation with too high of Dynamic compression ratio can cost 40-100 hp and same in Ft/lbs torque output at the Flywheel.
These Dynamic compression ratio calculators are far from optimal perfect does not account for Wet flow any, Fuel shear, different combustion chamber designs, ect.
My 455 Revs up like a $50,000 dollar 410 cubic small block Chevy Dirt Track engine with Crower Titanium lightweight Connecting rods.
No Titanium rods in my engine.