440RB INDY DUEL PLANE OR RPM INTAKE HELP

I did weld up an M1 like that for a 383. Used it on a 451 stroker. Ported 452 factory iron heads, 950 cfm Quick Fuel carb, $45.00 2" spacer off eBay, 9.5:1 compression, Comp Cams XR292R solid roller. 588 lb-ft @ 4,600 rpm and 621 hp @ 6,100 rpm. All this back on March 3, 2006.

The dyno operator says, "How the hell does that little engine make that horsepower with them little tiny Mopar ports?"
How much spring did you have.
I was just stuffing around with springs and i ended up at 220lb seat and 500 open