I am building a 331 stroker in my 89 lx, and have bought all C.A.R.B. legal parts so far. My question is could I run 10.5:1 CR and still pass CA. smog? I tried searching, but had no luck.
There really is no definitive way to answer that without you trying and telling us.
Most folks hope to pass smog with bolt-ons on a stock short-block 5.0 with Compression Ratios (depending on combustion chamber volumes of their heads) between 8.5-9.5:1.
Other people I know run CHP's CARB-smog legal 347 stroker short block, but in order to make that 347 smog legal CHP had to use different pistons than they normally do, though I'm not sure on the details of the compression ratio/cc ratings on that kit.
Even if there was another guy on the board running 10.5:1 compression and managed to pass smog, your combination of parts (even though they may all have CARB #s) may differ to the point that puts you over the top on emissions.