Edelbrock heads

Aluminum heads allow for a point higher in compression roughly but it depends on your camshaft as well.
http://www.enginebasics.com/Advanced%20Engine%20Tuning/Static%20vs%20Dynamic.html

I have a set of eddys on my Spirit. The pistons are autotec with 26cc dishes in them that gives me about 10.5 to 1 on the 420 stroker. I run 91 non-oxy premium with no problems. I wouldn't go much higher than that on the comp ratio.

The answer to your question in part depends on the highest octane available locally AND the compression ratio of your engine.
Here where I live 91 octane is all that is available at the average service station, typically in the S.W.
So of your compression ratio is pretty much anything over 9:1 an octane boost or AV gas is going to be required.
If you have 93 octane gasoline easily available then your 10.5:1 is going to be pretty much safe. Depending of course on how you tune things. But don't drive too far from a 93 octane pump.
Just keep in mind, detonation causes pistons to break and feeding your ride the proper fuel to run it is a whole bunch cheaper than fishing broken piston parts out of the places that can get into.

John, remember that with AL heads you can run a bit higher compression than iron, as they dissipate heat better. So your 9:1 becomes 10:1 on premium pump gas. Personally, I'd stay in the 9.0-9.5:1 range and not go as high as 10:1. Formulation for gas changes, and you may not be able to get 91-93 premium in years to come. I like a little lee-way too, don't like running right on the edge. You can always reduce timing if you are traveling and can't get premium temporarily, or use octane booster in that situation. Most likely if you're running real high compression you're not going to be taking many long trips though...

I'm right about 10.25 to 1. Custom Diamonds pistons. Comp Cams standard hyd cam. Full roller rockers.  If you are really interested the specifics I can dig up the parts list and engine build details.