Starting my turbo build
I don't know how much power you will make on 8psi, that depends on the size of the turbo and the tune. That being said, I don't know if 42lb injectors will be enough. I assume they will, but don't take my word for it. THAT being said... I don't think 42lbs will be enough while using E85, as E85 requires aprox 30% more fuel at WOT than gasoline.
E85 is much "Safer" to tune with and make power with than 93 octane gasoline. I have heard people say that they have tried to run tons of spark advance just to see if they could get it to knock, and they could not. That doesn't mean you should try it though. What that does say is that there is a lot more room for error when tuning with E85 than gasoline. Also it is capable of making more power than 93 octane.
Is E85 "Better"? I wouldn't open up that can of worms. You will start a massive debate. Bottom line is though, that E85 has proven itself to be a VERY competent alternative to high octane gasoline.
Good safe full boost AFR on gasoline would be 10.5:1 -11:1. You won't make as much power as you possibly could running leaner, but it will be safer.
If your tune is good and there is no knock, then the stock bottom should hold up to 8psi. There are people running WELL into the single digits on stock bottom ends.

