The reverse flow cooling in the LT1/LT4 engines allows it to get away with higher compression than a gen 1 SBC. On a LO3/LO5, I would go 10.5:1 with AL heads, or 10:1 with iron heads max, and either will require premium gas. Of course how much static compression you can get away with depends on lots of things, expecially the cam. Generally though, 11.4:1 will reguire higer octane racing fuel.
For a turbo motor, I would run about 8.5:1, but performance will suck terrably until you get the turbo on it.