440 power gains/ aluminum head advantages?

Pontiac Lemans 3950 lb without driver, first drag race experience. 455, Hi Port alum heads, headers, factory RA4 intake [ dual plane ], 236/230 @ 050 hyd roller cam [ note less exh duration ], 3.31 axle, T400, street tyres, not a Holley but a Chrys 850 TQ prepared by me, 11.78 @ 115.