11 second dart help

I went 12.5s @ 105 in a 71 swinger, Junkyard 360 magnum, 4.10 gears, PTC 2800 stall shifting at 5000. Thats how mild it was. Juiced it with a 125 shot & went 7.4s @ 96 in the 1/8, I had to back off the throttle a bit on that pass, That 383 should run 11s with no issues.

Now on my 75 Duster, Had a mild 451, stock 906 heads, FW headers, 9.73 compression, XE284H cam, M1 intake, 750dp, PTC 4400 stall, 4.10 gears, Ran a best of 10.91 @ 120.56 on a 1.51 60ft., I shifted that combo at 5600