IIRC that manifold was the smaller Indy 426-2 (4150 flange) w/ the dominator adapter on it? The only 2 worth running on a big motor are the Ray Barton manifold or the big Indy 426-4.

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