[mattfranklin]

Theoretically 11:1 gives you more power *and* fuel economy.
It's like free money.

The only catch is that your octane or knock resistance must support that.

As you know, late intake valve closure as it helps lower your peak pressure and lowers your dynamic compression ratio.

The personal data I have was taken over 30 years ago as part of a masters thesis focusing on engine knock.
Engine: 350 Chevy
Cam: stock
Compression ratio: 10:1, from cc measurements of combustion chamber and piston top
Fuel: regular, premium, and 100LL aviation fuel
Speed: 2400 and 2800 rpm on the dyno

With premium and 100LL I could run full spark timing sweeps to find MBT (max brake torque) without any trace of engine knock. It did knock with regular around best timing.

Note that this was with a clean combustion chamber, free from any carbon deposits. Typically, new or rebuilt engines continue to build carbon deposits up until ~15k miles. As the deposits build up, the engine's appetite for octane increases by several points. You can use a combustion chamber cleaner like Techron Concentrate to get you back closer to new.

That was in grad school, 30+ years ago.

Fast forward to a few years ago when I built a clone of a '70 LT-1 for my '70 C10...
I was so tempted to go to 11:1 like a true clone would be. I know the mechanical cam was fairly aggressive, and the late intake closure would help lower my dynamic compression ratio. Still, I didn't want to risk being stuck with having to severely retard the timing in case my estimates were off. So I took the safe path and went with 10:1. I know I could have done more, given my cam, but I didn't want to redo things.

If it were me, I'd go 10:1 again. If I were retired and had lots of time to rebuild the engine a couple of time a year, or wanted to fiddle with the complexity of water injection, I'd probably go 11:1.

How's that?