400 Non Stroker Build

Icon will give estimates of compression ratio on their website. Im guessing your 902 would have around 90cc. Icon says thats 8.9 with kb240. I dont know what the cc is on steaths, but if its 75cc, icon says a shade over 10 to1. That might be real iffy on pump 91.
But then, there are a whole lot of other factors than can make or break a pump gas combo.
I do agree with RRR, you might want to build it with stock replacement cast pistons, use the stealth, try for 8 1/4-8 1/2, and build a mild combo for 87, to push that c-body around.