I think a fully ported set of -1s, a custom roller, bigger headers, and the -3 intake will get you there. Talk to Dwayne Porter. I was in the process of building a 4.25" stroke version of the same type of setup you have before I bit the bullet and built my KB block hemi. My car is similar weight and I also wanted 9s NA on pump gas.
My plan back then was a 511" RB w/ the big CNC ported Indy -1s.
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
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