What the max hp using stock magnum heads

I had this combo for years, stock 5.9 with a cam and springs. 9.5 3800 stall, 4.10 gear, 1 5/8 jr headers, air gap and a 650. 12.20 on motor 10.90s on a 150 shot. 3300 lb duster
Similar, 750 holley, 3.91 on a 24.5 tire= 4.30
3500 converter, same 3300,
I will be tickled pink with 10.90