I mulled over this question for a long time, read everything I could and talked to several people I respected. I settled on 11.5 in my 413 smallblock. E85 with a 6-71 and mechanical injection. Haven't run it yet but I'm getting very close.

I went with custom dished pistons and thick cometic gaskets. I went this way so that if I didn't like the blower setup it wouldn't cost a fortune to put thinner gaskets on it and have fair compression to run race gas.