Did you do any tuning? Optimizing the AFR and timing could be worth another 20-30 hp/tq.
My 455 makes slightly higher numbers, but at lower RPM (less CR, smaller cam, so as expected). I've got a lower restriction exhaust, and a LOT of tuning (EFI & ignition control).
My car is a '73 T/A clone, 3.08 gears and stock torque converter - it has ran 13.12 @ 103.2. With your lighter car and more gear, you should easily be in the 12's (with traction!).
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'73 T/A (sold). Low budget stock headed 8.3:1 455, 222/242 116lsa .443/.435 cam. FAST Sportsman EFI, 317rwhp/385rwtq on 87 octane. 13.12 @103.2, 1.91 60'.
'67 Firebird [sold], ; 11.27 @ 119.61, 7.167 @ 96.07, with UD 280/280 (108LSA/ 109 ICL)solid cam. [1.537, 7.233 @93.61, 11.46 @ 115.4 w/ old UD 288/296 108 hydraulic cam] Feb '05 HPP, home-ported "16" D-ports, dished pistons (pump gas only), 3.42 gears, 275/60 DR's, 750DP, T2, full exhaust
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