870-900hp is plenty to run 8.90 at 3100, but the car needs to be on point. Well within the reach of a good -1 head for sure. I personally would likely use a B1 head(I know big surprise)but we always wanna go faster dont we. So why max out a head when you can have ore room to grow. Dyno numbers are dyno numbers but an HONEST 875 should get you there in a good car. Its simple math. FWIW my old Valiant went 9.0s at 150 with a stock block 511 with a B1 originals at 3470lbs.

Wes sent you a PM, just curious if its still available.