I know this isn't on my 5.0, but on my '65 Fairlane with a 289 I am running AFR 165cc non-emissions heads with an Edelbrock Performer RPM Air-Gap intake, 600cfm carb, Comp Xtreme Energy cam .493/.500 advertised lift (the entire valvetrain is Comp Cams stuff), MSD 6AL, MSD Pro-Billet Distributor, Hooker Super Comp Headers, 3.55:1 rear end gears, etc, etc.
With that combo, the motor has tons of low end torque and screams from 2500 rpm to 6000rpm. The heads would have no problem supporting more than 6000 rpm, but my stock crank/rods/cast pistons in my 289 won't!