I have not remodeled the engine in DD2003 but when I was planning the L31 injection prior to finding the PF4 and prior to using the dual plane MPFI manifold and the tri-Ys, I modeled it with a Sequential EFI manifold, 650 cfm of throttle body flow and a decent exhaust without headers.
492' cam 10.1:1
RPM-----HP-----TQ
2,000---133---349
2,500---180---377
3,000---230---402
3,500---273---410
4,000---302---397
4,500---322---376
5,000---326---343
5,500---314---300
Rule of thumb is 0.450 lb/hr/per hp B.S.F.C, but I have seen a lot of Vortec head engines running closer to 0.400 lb/hr/per hp. 29 x 8 / 0.4 x 0.57 = ~330 hp. The 77% duty cycle may have been a fluke the other night or due to the mine shaft like DA in the cool ~40F air. The engine was also still fairly cool, around 170F when I hammered on it then. Definitely similar to a "HERO" dyno pull or cooled down 1/4 mile track pass, not something maintainable on the street in normal driving. It definitely went like a bat out of hades though and there is a 100 ft long ~10" wide black mark from the right rear to prove it down the street from the shop. With the engine heat soaked and~90-100F intake air temps the air was substantially less dense yesterday too. ~300-330 hp is probably more in line with what the mild cam and aftermarket Vortecs are delivering power wise on this. Without the intake restriction, it might hit 350- 360 hp. I will model it later again with a dual plane and headers and reduce the intake tract CFM down to where it models the same ~1.6 in/hg restriction at ~5,500 and get a revised estimate. Then I will run another simulation with the full 1,000 cfm of flow the throttle body allegidly supplies to get an estimate of how much the current induction is hurting it.