How are you launching it? 60 foot?
That cubic inch making that kind of power is gonna have a pretty high torque peak. My 575" hemi makes similar power and needs a 5,000 rpm launch. Yours should be a lot higher.

CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax